Yep. That certainly made people remember my name. Wish the Shard kept track of all the reps, followers, and harder information with dates and all like google does with... everything. It would be so interesting to see all the data.
I will say if you want rep points, Memes, fanfic, art, and other creations are a big one, as most people will want to like something with that much effort and the joy they had seeing it (And even small stuff like messed up quotes.), then it goes to theorizing and posting on the discussion boards, especially if you had a good idea or point, and RPs and games don't really give much. For posts, it's actually the reverse, where RPs give you plenty (games don't count as posts, so RIP that), Theorizing, especially if you're like @Frustration and really active, will give you plenty (Koloss, if you remember, the first time we met, you were surprised by me having 400 posts in two weeks from nothing but the Cosmere threads. Wow, have I slowed down.) and creations are really time-consuming so you can't put them out at a constant rate.
I have no idea how to get followers (This coming from a guy with over thirty), and I tend to PM people who follow me what made them decide to, what thread/post, and some of them legit just shrug. The leaving your mark thing and constant posting is probably the closest thing I can see to a viable reason. I will say I tend to follow people who I see a lot, have lots of posts (Which is a sign that they are highly active for me), and I like what I see. However, things can be complicated when you take into account people decide to follow someone because they're friends with someone you follow or because they are popular, or a lot of other factors. Following people makes as much sense as the people following them, which is basically none. Because when have humans made sense?
I am still a fairly new person to the Shard (Only been here a little over four months) and am clearly somewhere in the middle of the whole popularity scale, smaller than those like Fadran, Frustration, Honorless, Storming AON ENE, but bigger than Cynical and... others. However, the ones who are bigger are also people who have been here far longer, and the people I am bigger than have been here even less than I have. So as time goes, if you have left enough of a presence, you will start to grow, from what I can tell, especially since people will rep old posts, particularly memes, which get repped even after several months.
And one's mark... no idea. I definitely did not think that I would end up being best known by my whole 'pinging Chaos' fiasco, no matter how funny it is looking back on it. Completely unintended, and I had been trying to build myself to be more of a theorizer or a writer, so i was plenty surprised when that event was what stuck. So I don't think you can really control what your mark will be. Pretty sure Fadran got popular with his RP FotT and had no idea it would blow up. So, my advice for a mark is just trying and do whatever it is that you do, and eventually something will stick with everyone. (You're already somewhat known for the Tin Cult and fun questions.)