God, it seems like an age ago I did that. Surely it's changed in 2 years? Personally, I detest 'team' excercises and usually find a way to get stitched up. Best of luck though.
Remember everyone's name and engage them and refer to them by name. Ask the quietest one in the group what he/she thinks. Volunteer to be a timekeeper and ask straight away if there is anyone within the group with relevant skills to the task. If you do all of that, they'll eat you up and gladly lighten your wallet! ;-)
Don't be phased about the interview, it's the easiest part. Probably be a good cop/bad cop routine. Don't get phased and be chatty and for gods sake if you don't regularly read Flight then don't lie, because they WILL ask you a question on a recent piece if you do!
Compass tests - try to leave the hand of Beadle at home and always carefully read the instructions before starting each bit. Spend the time reading and FULLY UNDERSTANDING these and you shouldn't (insha allah) make a cock of it.
Physics/science test - GCSE textbooks, get one if you don't have one already! It's really a mechanical reasoning paper so don't go studying organic chemistry for gods sake!
Finally, remember why you are there. YOU, as well as THEY need to be sure that this career is for you and more than likely, if you are successful they will be the people putting you forward for jobs. So for gods sake, be nice to everyone, smile politely, drink as much of the freebies as you can, and say hi to the lovely Claire because she looks after everybody and is your first port of call when you finish the APP.
Best of luck all.