Late to the party, but I'll second the advice about participating in other RPs. It's fun, for one, but more importantly, it'll build up a portfolio of posts that prospective players can use to gauge whether they'd jive with you in your own RP. 

For me, the very first thing I do whenever I see an interest check that catches my eye is to look at the GM's recent posts. I want to see if this is someone at a similar writing level to me whose style is enjoyable (or at least tolerable) to read. If there aren't any recent posts, I usually lose interest. I reckon a lot of people on here are probably the same. 

Also, I'll echo the point about posting in General. Nobody checks General. Personally, I'd post everything in Casual; posting in Advanced usually gets a lot less traction and attracts a more... persnickety crowd, so to speak. But there's no shortage of RPs in the Casual section whose posts outclass 90% of the published works you'd find in a bookstore today.