HEYHEY!!! Just be yourself, as .. literally everybody else has said. I wouldn't count myself as popular, but somehow half the server still knows at least one character I play. You seem like a super cool person, and the best thing I can suggest is to join a faction or team.
Factions are always tons of fun. I've only been in two, but both got me friends almost as soon as I joined and raised my popularity.
I don't have any sports team experience, but all my friends tell me it's super fun ... so I say go for it if that's your thing!
And remember to be nice to people. When you're nice and talk to people, (or get around,) people tend to stick and remember your name. Don't stress it too much, as being 'popular' on a Minecraft server isn't that big of a deal, but I can understand where you're coming from. Try to get yourself out there, have fun, talk in OOC, and find your people.
Don't focus on being popular by any means, but it certainly gets you places, from what I've seen. What matters most is that you're having fun, and don't feel stressed.
Happy roleplaying, I'm sure you'll do great things on SRP.