We Examiners know you won't be perfect, but equally you can't expect to have a go at everything twice.
Normally I'll start by chatting through the trip with the 'applicant' as JAA describes you, give him/her the navigation route and then leave him/her to plan it whilst I have a cup of tea and check the paperwork. We're actually supposed to collect the fee before we fly with the applicant, incidentally - but few do!
Then it's out to the ac after booking out; I normally watch the applicant doing his/her pre-flight checks and ask the odd simple 'oral question'. Then in we get, crank up and putter off on the navigation section. First leg I will play the quiet passenger and will let the applicant get on with it - but ask for the ETA and also for any decisions regarding alteration of heading and revision of ETA to be made known to me. On the second leg the applicant will get an unplanned diversion. Personally I ask the applicant to show me where we are (when there's an obvious feature coming up) and then say "Weather ahead has deteriorated, when you are ready, I'd like you to take us there" - and pass over a page from Pooley's, showing the applicant roughly where 'there' is. Just before we set off towards 'there', I'll ask for a heading and ETA; on that leg please feel free to augment your flying with some map reading. When we get to 'there', we'll either do a join and circuit to go-around - or just climb up and get on with the general handling. But I will be looking after the navigation at that stage. Expect to climb up, FREDA check, then a couple of steep turns including a recovery from a spiral descent. Then a few stalls, settle back down and turn onto a heading which I'll indicate. After a short while I then get the applicant to fix position by use of radio nav, then track towards a beacon for 5 minutes - the last couple wearing foggles to get used to them before flying the 180 deg IF turn. Then foggles off, fly as directed and we'll have a simulated icky-poo engine leading to an off-aerodrome practice forced landing. Overshoot from that, climb up to about 2500 ft at best angle of climb, including the odd turn. The applicant will then be somewhere he/she knows well - so it's "Let's go home for a few circuits" time. Join, normal, glide, flapless, sim bad weather plus the inevitable EFATO and low go-around. Final landing, taxy in, shut down - then the YES/NO verdict.... The huge majority get a 'YES'!
We'll then refuel the ac, tie it down and wander in - I make the applicant a cuppa before we have a chat about the trip and I do the paperwork whilst the applicant grins like a Cheshire Cat!
We know you'll be nervous, we'll try to make you relax. Just enjoy showing us what you can do!