hmm seems to be asked a lot, maybe i should do a blog post on this.
basically like in this shot i have 5 different shots. choose 1 to be your main one and layer and mask all the others, and crop the outside or all the other layers besides the one you are using as your main one making sure that you dont let things later in the sequence overlap things that were earlier in the sequence. If you don't understand shoot me a PM and ill do my best to help you out with any questions you have.
If at first you don't succeed, failure may be your thing-Warren Miller