First of all, "becoming popular" shouldn't be your intention when on MCSG. Many people are famous for their mishaps and all the things they've done wrong. A better way to look at it is how to gain respect. I'd much rather be not very popular, but people respect me, than everybody knowing me but nobody respecting me. If you want to become respected, the main thing to do is to not spam the forums.
You should actually put some time and thought into every one of your posts, and make sure they're relevant to the topic of the thread. Also don't spam people's profiles, it gets annoying. You also don't need to play a lot in-game to be popular. I would consider myself semi-popular and I haven't played a game of MCSG in at least two months. And remember; becoming respected or well known takes a lot of time! Make sure you're consistent with your posts and you will slowly begin to gain some attention.