Aaaah C3, my old friend! You've grown up so fast; I was active in the 2014 thread and now we're looking at 2015 already!
On a more serious note, good luck with C3 everybody! I would say that the best bit of advice I can give is to practice trigonometry until you see it on the inside of your eyelids. That, and remember not to neglect functions! The calculus stuff is a cinch.