I suggest having two friends or handlers at the meet. If you have none, make some friends. People are extremely nice at meets. One handler will help deal with your gear, get you water, helping you decide what your 2nd and 3rd attempts will be and tell you how many lifters are ahead of you. If this person is experienced enough he or she can help you with the timing of your warmups, as it varies in different meets due to how many lifters there are. The second handler will just take pictures and help out the 1st handler.
Of course if you don’t have this, just make sure how far you are out. Usually they will call stuff like _____ 3 out or 4 out. Then there’s In the hole means you’re two out and then there’s on deck, means you are up next after whoever is on the platform. If you are wrapping yourself, i suggest you wrap when you’re in the hole or three out. Afterwards, do not get all psyched, keep in mind to walk over to whoever’s dealing with the attempts and tell them your next attempt. You’re usually given a minute to do so. DO NOT FORGET. I almost did.
As for how to warmup, bring a foam roller and roll till everything is nice and loose. I’m not a fan of static stretching before lifting but to each their own. And speaking of that, everyone has a different warmup style with the lifts. Someone who squats 500 will take longer to warmup than someone who squats 300. But I think the guidelines that Tim Henriques pointed out works for most.
The USPA is not drugtested AFAIK. I’m not sure who decides but from what I’ve been told USPA doesn’t drug-test. If it’s a small meet and you’re not breaking world records I don’t see why they would drug test every single athlete. That is a major punch in their budget. However don’t take my word for it. You can also just go in an untested division like it has already been said.
Good luck and have fun.