I started as a (very) tall, muscular guy, because I haven't any other mean of give to my avatar a particular feature. I decided to go bald because back in those time SL hairs really sucked. The handlebar mustache came because I wanted to step out of the typical "Don Johnson" drawn mustaches and beard of SL skins. I always liked fancy suits in white or other unusual colors. The final product was a guy who looked like a Victorian strongman/boxer, and since I was actually a regular on Steampunk/Victorian sims, it fit really well.
Ten years passed, and my avatar looks pretty much the same. Some improvements like better proportions, Niramyth Aesthetic mesh body, but still in fancy formal suits. The face looks older, and I actually like that, because maybe (just maybe) time passes for SL's avatars also.