Shooting a spider hanging from a web is tough, since the slightest little wind can move it out of the plane of sharp focus. If you are trying to learn then it would be a good idea to shoot something more stable.
IMHO shots taken from directly under, or directly over the top of, a critter just don't work. It's best to shoot from the side like this:
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Use the basic rules of composition when you shoot macro -treat it like any other photographic discipline. If you take all of your shots from the top or bottom and centered you won't stand out from the croud...
Also see my blog (link in my signature) -lots of macro tips there.
P.S. Sorry about posting an image to your thread -was easier to show you than to explain it
