Same with me. Though I have been flying for nearly 4 years now, I still get nervous. Most of the nervousness is before the first flight and, strangely, in the 2nd flight when I ususlly shake in my thumbs.

Probably I am too focussed in the first flight to shake and in the second, I usually do all my aerobatics and most of my mistakes. When that happens, level your airplane going into the wing and tell yourself "Relax, relax". I found it helps. It also helps if you take risks (aerobatics) progressively rather than all at once

Ameyam