One thing I tend to do when I get nervous is make jokes, and usually the best ones are about my own shortcomings. Recently I've been thinking thought that maybe this isn't a good thing to do around girl. I just really want some input, I never try to play the "clown" but I've never had a problem about laughing about myself and things that go on with me, but does that just paint me in a bad light?
If you're interested in a girl, self-depricating humor is not the best way to go. You will seem insecure and she will become aware of your short-comings. You don't want to set yourself up this way. It's okay to do it once in a while or after you've known her for some time but try to use sparingly here.
Well, I've got to say that I do this myself so I can't really tell you not to. :/
I wouldn't say it paints you in a bad light. It just leaves you vulnerable. If you're okay with that, then go right ahead. I've got guy friends who do this, some of which I do like or like me. It doesn't bother me, and I don't like them any less because of it. lol
It's better than if you were constantly going on and on about how amazing you are at everything. That gets to be rather annoying.
I'd say go for something in the middle there. A few jokes about your shortcomings and a few jokes about how awesome you can be. :D
I'd say it might not be the best way to go and should only be used very occasionally until you know her better. It will make you seem like you are insecure and that nervousness will be apparent to her. If you do it to get a laugh out of her for something you did, it might be OK. But I'd say to not attack yourself because she really can't see what you mean behind your jokes, only what she hears.