The DVSA publishes annual data on why learners fail their driving test, and the same faults appear at the top of the list year after year. Knowing what these faults are (and understanding how to avoid them) gives you a considerable advantage.
The most common serious fault is poor observation at junctions. This includes pulling out when it is not safe, failing to check blind spots, and misjudging the speed of approaching traffic. At every junction, slow down early, check your mirrors, look both ways, and only proceed when you are completely certain it is safe.
The second most frequent fault is incorrect mirror use. Forgetting to check before signalling, changing speed, or changing direction costs marks repeatedly. The examiner watches for mirror checks at critical moments: before junctions, roundabouts, lane changes, and manoeuvres. Make your checks clear and visible.
Steering control ranks third. Hitting the kerb, mounting the pavement, or failing to steer enough through bends are all avoidable with correct hand position and looking well ahead.
Other recurring faults include poor lane positioning and corner-cutting; unsafe moving off without proper observation; loss of control during reversing manoeuvres; failure to respond to traffic signals and road markings; and driving at an inappropriate speed for the conditions.