I've so far fallen short of actually getting a roleplaying site up and running. It is mostly because of my own shortcomings and other factors that play a role. Here are some tips that I found from the internet of which I probably will never try:
1) Get your friends or family involved (like that is ever going to happen). This is most likely all for the "gathering a core base".
2) Advertise (been doing this) and affiliate (so many restrictions). I pretty much suck at advertising something. It's not my forte so to speak. I just have to get better at it. I tried copying a format of what someone else did but it hardly worked.
3) Remember to be there at the site when others look into it. My biggest fault is that I'm not there watching things.
I know it is hard to actually run a site/forum devoted to RPing but I think I have bitten off more than I can chew. The best option is to keep pressing on and hopefully find people who might like the RP that I'm doing.