You generally gain cred by being around, making yourself seen, contributing to discussions, and things like that.
I'm known for my threads about sex and relationships, which generally involve polls. If you see a thread about sex on here, it's either mine, or will have a comment by me at some point.
If you're just going to post in other people's threads, just pick an avatar that stands out a bit, and you'll be fine. I'd change mine, but I've had it since day one, and people recognize me by it now. If you're going to make your own threads, try sticking to a theme, or try to post things that have high discussion value. That's really how you get known. It's pretty hard to actually have bad cred here, so unless you're aiming for that, you'll be accepted by most of us.