It might help you on the radio to remember that the ATC guys are people too, not gods. We're all on the same side, trying to keep things running smoothly and safely.

While this generally requires talking quickly and precisely, if you should mess up a little, they are not the enemy (even if they sound a bit gruff). They'll correct you, help you, and move on.

I definitely had radio troubles at the beginning, and remember when I recognized that the guy in the tower was a trainee who had even less confidence than I did. When he didn't get a call exactly right, I helped him out, and we kept the system moving.