Things to do before animating

I’ve just finished drawing all the models that I’m going to use in my first flash movie. Is there anything I should do/check before starting? Also, how do I lower the size of the drawings, becasue some of my files take up around 10 mg of space…something is definately not right there. Oh, and should I make my audio file first, or is it okay to start animating and leaving the audio for later? Sorry to throw a lot of questions at ya, but I just don’t want to start over becasue of some minor details that I missed.

Thanks in advace,