It's soooo easy. First off, just take it easy. If you do something ridiculously slow, they won't rush you or care. When you first get in the water you'll get a little apprehensive, but after 3 minutes or so it goes away. So just take your time, and use your head!
I went from crystal clear pool to murky lake. I actually liked it in the lake better, because it was a natural environment.
About the full mask removal, just take your time. Remove the mask, and keep your eyes closed. The second you open your eyes you may panic. Keep them closed, and remember to BREATHE! Your mask isn't your regulator, so you can still breathe with it off! Many people forget about that. Slowly put it back on, and then it's easy from there. Even if it takes your 100 blows to clear it, you'll be fine.
Good luck, and HAVE FUN!