a big community is a must. tell all your friends about it, even those fair-weather freinds that you only talk to when everyone else ie busy. in addition, make browsing the forum all-access. (if your hosting company puts a file in your space called robots.txt, delete it. you want places like google to get to your site.)
in fact, you might want to allow anonymouse posting for a while, at least until you get enough members.
DO:
--Advertise to freinds and on your own sites.
--Allow posting from anyone, even if that means manually pruning the spam and nastiness that pop up from immature babies who are losers even by intarweb standards.
--use a easy to read color theme. ask an art student to pick colours if you dont trust yourself.
DO NOT:
--Spam. this will actually get people to NOT visit your site, and may even earn you some enemies. people will not only not visit your site, but they'll tell other people not to go, also.
--use black background and red text, or vice versa. its friggen overdone to all hell. i like the pink and yellow of 4chan, but not everyone does. if you cant decide, pastel blues and silvers make a good default until you get something better.
--forget to proofread your entries, and make at least some effort to to make and promote intelligent posters. spelling errors by the mods or admin make the site look bad.
--be afraid to delete retarded posts. nip Dee dee dee threads in the bud before the balls touch, mmmkay?
--make a habit of using in-jokes and refering to IRL events on your forum. a), putting identifiable information on a public site is just plain poor sense, and b), you'll probobly alienate your intarweb freinds who don't know what your talking about.
>>5 is right. think of forums as your time mage of the website Party. sure, they get sweet things like Haste, Slow, Stop, and Confuse, but without a way to take adantage of it, its useless. make a site of some kind. a fansite, a linkdump, a simple fangame, whatever. even a fanfiction community, if you're into that kinda thing. Even Gaia has this psudo-game kinda thing going on, not to mention its like a huge linkdump with tons of anime sites.
Main website: Fighter. main player, frontline soldier. does all the gruntwork.
You: White Mage. keeps everything working properly.
Downloads page: Black mage. Costly and high-maitenence, but highly effective.
Forums: Scholars/Geomancers/Sages/etc from FFIII. kinda sucky, but have the ability to turn a mediocre site to a friggen awesome one.
Good luck with the website, dood!