I'm Shazzbaa, and my webcomic is Runewriters, a fantasy comic about ridiculous friends, strange magic, and occasional lovecraftian horrors. I tend to be wordy on the forums. xD
My avatar is an illustration of me -- I drew it right after I got my hair cut short and wanted to figure out how to draw my new look!
On one of my first forums I suddenly noticed that, despite the fact that I know people don't always look like their avatar, I associated everyone's tone of voice and identity with that little picture they chose to represent themselves. There was one lady on the forum who always tended to seem kind of condescending, though I wasn't sure why... until I noticed her avatar was this snooty-expressioned drawing of one of her characters. I knew it wasn't her, and I'd never assumed it was her, but subconsciously, that was only thing my brain had to go on, so I'd been reading all her posts in that tone.
So my rule from then on was to pick an image that's friendly-looking so that my posts would hopefully come across that way! I would also try to pick something non-masculine since, at the time, people online tended to assume everyone was a guy. Lately I use drawings of myself -- my first comic was a journal comic, so my actual appearance is a kinda big part of my brand!