First of all, you must realise that a learner driver does not have the same experience as a driver as you!  (I know that this sounds obvious)  If, for instance, a situation happens that the learner has not anticipated, they might just suddenly use the brake and come to a stop.  This is alright as long as the road user behind can stop without causing a collision.   Also, without dual controls the accompanying driver cannot stop the car, change gear or de-clutch.  (There are more claims to insurance companies from learner drivers practising and hardly any from learners in lessons)

So, I suggest that practice is done when the learner has completed all of the topics advised by the DSA and they are reasonably competent.  The accompanying driver needs to be there only for legal and safety reasons.

All learners are taught a routine that is to be used in every situation whether it is MSPSL (mirror, signal, speed, position, and look), a way of approaching junctions or how to do a manoeuvre.  Ask the learner what the routine is and help them improve on it.

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When approaching a hazard (something that makes you change speed or direction), you must be at the correct speed, gear and position.

The pupil will be taught that they use the accelerator and/or brake to slow down and when the appropriate speed is achieved change to the gear that is best suited for the hazard.  They should try to avoid overlapping braking and gear change so that they have more time to assess the correct gear and get back onto the accelerator pedal.  
If travelling downhill, then a slight overlap of brake and gear is ok.

The correct gear depends on the type of engine and not the engine speed.   Just because the engine copes at 20mph in 4th gear does not mean that you are being economical!  A higher engine speed (2500-3000 rpm) means that it is less effort for the engine to move the car and not necessarily costing more fuel.   As a rough guide: 2nd gear at around 12mph, 3rd gear 21 mph, 4th gear 37 mph and 5th gear 48 mph.   This does vary from car to car.  Look in the car manual to check.

Changing gear should always be planned and never rushed.  Trying not to grab the gear lever, but gently and positively select the gear.  It should take between 3 and 5 seconds from start to finish when changing gear.

Using mirrors (or appropriate mirror/s) is a very important part of getting information for safe driving.  A learner will use his or her mirrors out of habit rather than out of a need for information, so it is important to reinforce the reasons behind the use of mirrors.

There are several situations when mirrors should be used: before changing direction, before changing speed, before signalling and just generally keeping track of the vehicles behind. 

Door Mirrors

If a change of direction is needed, then the appropriate door mirror is used to check for any vehicle overtaking you.

Rear View Mirror

On a risk assessment scale, checking the rear view mirror isn’t so important compared to checking the door mirror.  But, if a vehicle is closely following you, then an early signal from your brake lights should make it safer to slow down.  Plus, if an emergency vehicle is behind with only the flashing blue light on, you might have to re-assess whether you can slow down without inconveniencing them.

If you wish to speed up when the speed limit increases, check your mirror before doing so just in case another vehicle is overtaking you which would put that driver into more danger as they endeavour to get in front of you.

Before signals

If you observe someone is about to overtake and you want to turn right, to (hopefully) stop them from doing so an earlier than usual signal is needed.

I have given “when and why” reasons for the use of mirrors but not the “how”!   The quicker the mirrors are used the sooner the driver can focus ahead again, so moving the head to glance in mirrors should be discouraged (apart from the nearside door mirror) and a quick movement of the eyes should be used.

Mirrors and reversing

“Mirrors are for position and windows are for safety”

There is nothing wrong with using mirrors as an aid to reversing as long as the safety of other road using is not compromised.

Looking through the windows gives much more information than from the mirrors, although the mirrors help with the positioning of the reversing vehicle in the road.

Moving off from the side of the road seems straight forward enough, but there are plenty of Learners who have failed their driving test on unsafe moving off.

The examiner will ask the candidate to pull up (park) on the left in a safe, legal and convenient place giving enough room to move off again anything up to 8 times during a practical driving test.  So, doing it well is important.

Pulling up on the left

Hitting or slightly touching the kerb is a common fault with learners (and some experienced drivers).  The cause is where they are looking!  If they look at the kerb, hitting the kerb is very likely.  But, looking ahead (perhaps focussing on a parked vehicle ahead) will stop this from happening.

Moving off

"Only prepare to move off if you will do so very shortly".

As mirrors and forward observation is being carried out, increase the engine revs to a lively hum then find and feel the biting point.   Quickly check the blind spot(s), signal and then release the parking brake.

Using signals

A signal is simply a way of showing other road users your intentions either by: direction indicators, brake lights, horn and flashing the headlamps.  The last two are used as a warning to show your presence to someone who perhaps might not know that you are there.

Direction indicators

They are used to tell others of your intentions to move off the main road to a side road, when changing lanes, moving off, pulling up and overtaking.

Sometimes, a signal might not be necessary if no-one will benefit from it.  As long as you have assessed that there are no hidden road users behind parked vehicles etc. 

Never signal out of habit, it should always be correctly assessed.

Signalling when passing an obstruction is very rarely needed as it should be obvious to everyone around what you are doing by your position in the road.

Brake lights

These can be used as a way of communicating to a tailgater that you will be slowing down.  Just a very light pressure on the brake pedal will switch on the lights.  Also, if you are stopped in a queue of traffic with the parking brake on and you see that a vehicle behind is approaching very fast, put the brake lights on.

Flashing the headlights

Only to be used to warn others of your presence when a horn is inappropriate or illegal

The horn

Like the use of flashing the headlights, only to be used to warn others of your presence. 

It is against the law to use when stationary (unless it is an emergency situation), in an aggressive way and in a built up area between 1130 and 0700.

If used in any other way, you could be fined around £70