I'll second what Glideangle said: Breathe!
I just finished AFF at my local DZ and I had difficulty relaxing up through level 4. I had a moment just after exit during a repeat of level 4 where everything clicked for me. I remembered to take a breath, looked up and saw my instructor telling me to smile, and I got a big thumbs up. After that all of my subsequent jumps have been smooth as can be.
Don't be afraid to take a second or two for yourself after exit to just relax and breathe. It makes all the difference in the world. I think new students(including myself) feel a lot of pressure to do all of the tasks they have set before them in what we perceive at first to be a short window. The reality is that we have plenty of time. Just remember to enjoy the experience and smile. You'll do great!