A basic list of some of the most common errors made by learner drivers.

STALLING. Common causes
Coming off the clutch too quickly.
Not setting the gas. Some vehicles will require the gas to be set first to assist the car when moving off.
Being in the incorrect gear.
Panicking because of a vehicle behind them.

POOR POSITION IN THE ROAD GENERAL DRIVING. Common causes
Spatial awareness of the size of the vehicle .
Looking just in front of their vehicle or following the vehicle ahead of them.
No future planning.
Position in the road at junctions.
Stopping short of Give way lines or stop lines at traffic lights.
Being too far away from the kerb when pulling in.

NO USE OF MIRRORS. Common causes
Habit of using them is not yet built. (early days of learning is common)
Fear of taking their eyes off the road.
Do not understand the reason why they need to use them.

DO NOT SIGNAL/SIGNAL EARLY/SIGNAL INCORRECTLY.
Common causes
Do not know how to operate them.
Do not know the rules behind using them.
Simply forget.
Do not understand timings.
Do not engage the signal correctly and on engage motorway signal.
Forget to switch signal off when exiting a roundabout.
Leave left signal on after pulling in, and then move off with it still on.

CROSSING CENTRE LINES WHEN EMERGING FROM A JUNCTION TURNING LEFT. Common causes
Position in the road is straight at the Give way line.
Did not plan ahead to see mouth of junction is wider.
Travelling too fast on approach.
Did not steer quickly enough when emerging.
Need to build on foot and hand control, doing both together.

RIDING THE PAVEMENT WHEN TURNING INTO OF OUT OF A JUNCTION. Common causes
Not looking into the road they are turning into.
Steering too early.
Steering too quickly.

BRAKING. Common Issues
Will brake late.
Will brake early.
Will brake heavily.
Will brake without checking who is behind them.
Every time the pupil brakes they also depress the clutch pedal.
Using the parking brake to slow the car.
Not releasing the parking brake when moving off.
Not using the parking brake on a hill and causing roll-back.
Not braking heavily enough when carrying out an emergency stop.

JUNCTIONS AND ROUNDABOUTS. Common issues
Will stop at a roundabout when nothing is coming. (No observations on approach)
Will Stop at an open junction when nothing coming. (No observations on approach)
Will not stop at a closed junction. No hazard routine used on approach, ending up with too much speed they then panic because they won't stop in time so just gamble that nothing is coming, without thinking about the consequences.
Will stop at a junction/roundabout but take ages to move off.
There may be numerous issues going on here.
1. Not comfortable with the clutch control ability.
2. Not looking in the correct direction at the right time to be able to make a judgement call.
3. May not be looking at all.
4. Cannot judge approach speeds of other vehicles very well.
5. Are looking for a much bigger gap rather than a vehicle to follow that has a reasonable gap behind them.
6. Are not looking for blockers.
7. Don't know what blockers are and how they can utilse them.
8. Panicking about what lane they should use.
9. The junction they have stopped at may have a limited line of sight along the road, the learner has not got close enough to the Give way or stop line and cannot see if it is safe to pull out. This is where creep and peep comes into action. Get them to creep forward until their line of sight has improved.
10. Regularly stopping short of a Give way/stop line. Generally by looking out of the drivers window and looking at the lowest part of the door mirror, the driver should be able to see the Give way line appear underneath the mirror. The car should not have crossed the Give way line at this point.
11. Do not keep in their lane while navigating the roundabout. (not looking far enough ahead)
12. Do not signal correctly either on approach or when exiting the roundabout.
13. Will not position in the road at junctions appropriately for the direction they are travelling in.

SPEED USE AND MAKING PROGRESS. Common issues
Unaware of speed limit for the road they are on.
Exceeding the speed limit.
Not making progress. No vehicles ahead of them and travelling more than 3mph under the roads speed limit. Obviously if circumstances require them to be slower (narrow roads, Parked cars, pedestrians etc) then they would be expected to reduce their speed. LESS SPACE=LESS SPEED.
Exceeding the speed limit. 2 miles an hour over the speed limit but reacted to quickly would normally not be an issue based on road undulations that may make the vehicle run away slightly, but this must be reacted to reasonably quickly. 3 mph over the speed limit in a 30mph would be deemed speeding.
Not keeping a safe following distance. 2 seconds minimum on dry road, 4 second min wet roads, 20 second min snow and ice.
If a vehicle ahead of your pupil is travelling at 30mph in a 40mph it can happen that your pupil sits too close to the vehicle in front of them because the get confused that they have to be making progress (no slower than 3mph under the speed limit) in this situation, your pupil is not the cause of not making progress, it is the vehicle ahead of you. Your pupil cannot be marked down for this. However, if the vehicle ahead of you is going too slow and there is a safe overtake possible, then an examiner may expect your pupil to make that overtake.

General rule of thumb.
1. Are their street lights / residential roads? Generally the speed limit would be 30mph unless otherwise stated
2. Are their street lights with repeater signs on them? That's the speed limit
3. Are there no street lights? Generally national speed limit applies unless otherwise stated.
4. Are they in a school zone? Generally a advisory speed limit of 20mph applies.
5. Are they on a dual carriageway? Generally, unless otherwise stated the limit is 60 or 70mph. 60 mph for cars if there is no form of barrier between you and oncoming vehicles (this could be grass, a concrete raised area, or Armco barrier) 70mph for cars if there is a separation area of grass, a concrete raised area or Armco barrier)
6. Motorway is 70mph for car unless otherwise stated by variable speed limits in place.

If repeater signs are few and far between and your learner is on a 40mph road and there are residential roads off of the main road, try getting your pupils to look into the side roads, it's highly likely that the side roads will have 30mph or 20mph change of speed limit signs on the entrance to those roads.If the speed limit signs are 500mm in diameter it means the speed is changing this would mean the speed of the road they are on is higher than that of the side road.


CLEARANCE Common issues.
Not leaving enough space when passing a cyclist. at speed up to 30mph a 1.5mtr space is required Speeds over 30mph a space of at least 2mtrs is required.
Horses. Speeds no faster than 10mph and at least 2 metres clearance.
Parked vehicles. At least 1 metre clearance, or a vast reduction in speed. Always teach your learners to be the defensive driver.
Road works. As much clearance as you would a parked vehicle or reduced speed.

GEARS AND ECO DRIVING. Common issues
Not using the gears correctly
Taking junctions in 3rd or 4th gear causing too much speed into the junction.
Taking junctions in 3rd or 4th gear causing a stall situation to happen.
Coasting into a junction or going downhill.
General driving and being in 2nd or 3rd gear when 4th 5th or 6th would be more suitable. The engine is screaming at you with 5000prm and your pupil is not taking action. (waste of fuel, additional engine wear, not environmentally friendly, additional noise pollution) 
Using higher gear when going uphill, thinking the higher gear has more power. Vehicle keeps getting slower and slower and no action is taken.
Putting the car into neutral on the approach to a junction or traffic lights so the car rolls up to the junction.

LIGHTS AND WIPERS. Common issues
Generally not using them when necessary.
With modern vehicles having automatic lights pupils don't get taught much about them. Where the controls are, what ones to use for certain situations, understanding that running daylight lights will, on most vehicles only illuminate the front light and the dashboard lights, there will be no rear sidelights on. Therefore, when it rains or is foggy, the pupil may be able to see the dashboard and vehicles in front of them, but their vehicle is not visible from behind.
If wipers are on, lights should also be on.
Pupils, not being proficient with use of the wipers. Automatic rain sensing wiper, Auto intermittent wipe and the facility to adjust the intermittency, slow on, fast on, single wipe.

STEERING. Common issues
Steering a car is not natural to everyone.
Hand eye coordination takes time.
One of the biggest misconceptions with new drivers is how much you need to turn a steering wheel. If they have ever driven a Go-Kart, it is well worth explaining to them that the steering on a car is substantially more input to get the same output as that of a Go-Kart.
Generally a car's steering wheel will rotate from one extreme to the opposite extreme by rotating the wheel 3 complete turns. At one and a half turns from either full lock, the steering should be straight.
There are possibly going to be times when you WILL need to intervene with the steering wheel, especially at the start of a learners training, until they have a full understanding of its use.
Pulling out from or turning into a junction is where the biggest steering issues tend to happen until your learner is comfortable with input-output method.
Generally, when travelling in a straight line, a new driver can tend to veer from left to right in their lane, this is usually because they are not looking far enough along the road. Get them to lift their eyes so they are looking 4 or 5 cars further ahead. Eventually they will find their groove.
When pulling in at the side of the road, it is very common for your lovely alloy wheels to take a battering. This will be because your learner keeps looking at the kerb when they pull in. Firstly get them to carry out the MSPSGL routine and get the car moving slowly, then allow the clutch to be introduced so that the are rolling, and then gradually steer toward the kerb. If they have parked vehicles ahead of them, try and get them to line their car up with the parked cars. They can always utilise the passenger door mirror to see how close they are to the kerb. BUT remember the front of the car will always be closer to the kerb then the rear. When there is somewhere between 100-200mm gap between the rear wheel and the kerb the car is close enough to the kerb, it does NOT need to be any closer. Getting closer will usually end up with the potential of tyre or wheel damage.
The best advice for your pupils is to NOT LOOK AT THE KERB WHEN PULLING IN. 



OBSERVATIONS.Common issues
Not checking blind sport before moving off.
Not checking mirrors before changing speed or direction.
Not carrying out effective observations when performing a manoeuvre.
Generally unaware of their surroundings during general driving.
Not keeping a tyres and tarmac gap in built up traffic.

SAFE, LEGAL AND CONVENIENT Common issues.
Pulling in over a driveway or dropped kerb.
Stopping in a bus stop.
Stopping within 10 metres of a junction.
Stopping on a tight bend.
Stopping on the brow of a hill.
Stopping too far away from the kerb.
Parking on the pavement.
Stopping in a school zone during it's time of use.
Overtaking on Zig Zags
Parking on Zig Zag lines.
Stopping over a Give way line or Stop line.

REACTIONS TO ROAD MARKING OR SIGNS. Common issues
Ignoring road signs (too focused on the road, or have no understanding of what the road signs mean)
Ignoring road markings (too focused on the road ahead, or have no understanding of what road markings mean)
Driving in a cycle lane with solid white line.
Crossing a single or double solid white line at speeds over 10mph when not turning into a premises or junction.
Entering a no entry road.
Turning right or going ahead on a left turn only road marking.
Jumping a red light.


These are just some of the general issues made by learner drivers.
You'll need to build your own skillset to spot these things and have a in-built sense to know that they may happen at any given time.

For new learners there may be times where you WILL have to intervene, if you are not prepared for these types of issue they could end up with a safety critical incident occurring.