The overwhelming majority of the PPL 'applicants' I've examined have passed first time with little difficulty.
Weak areas (this might help some of you to revise):
1. Forced landings
2. Not using a sound rigorous visual navigation technique but relying on feature crawling and reading 'ground to map'. This will INVARIABLY result in a partial pass at best.
3. Not listening to ATC and poor use of RT.
4. Recoveries from spiral descents.
To be honest, by the time you get to the Skill Test you should be good enough to pass without worry if you've been trained properly. Don't listen to all this rubbish about carrying bottles of water and chocolate bars - there really is no need. Normally you'll just take off and start your first leg of the navex with the Examiner just wanting to be told your ETA at the first turning point and any correction you later apply. He/she'll know what you're doing and won't comment unless absolutely necessary. On the second leg you'll get a diversion to somewhere - but you only set off for the diversion WHEN YOU ARE READY!! If the diversion aerodrome is amenable, I will require an applicant to join for an overhead join and a normal circuit and go-around. Once you've done that, the Examiner will look after the navigation and ask you to do a couple of steep turns, some stalls and will later introduce a simulated engine failure. You'll be told to go-around as soon as the Examiner is happy that you would have made the field; you'll probably then just climb at best angle with a couple of turns to look after the 'flight at critically low speed' requirement, then climb at best rate up to about 2000ft and set off home. On the way you'll fix your position at some stage by use of radio navigation aids except GPS or asking ground radar, track towards a suitable beacon for 5 minutes and then join your familiar home aerodrome for a normal, a glide, a flapless and a 'bad weather' circuit with an EFATO at some stage. And that's about it - at some stage the Examiner will ask the odd technical question to confirm your level of knowledge is OK, but it is FAR less stressful than a driving test, believe me!
But please make sure your FLWOPs are sound!!