Be Different!
This is the hardest thing to do when running a forum..
These days the internet is full of fansites, communities on all sorts of different topics. To get the forum kicked off you must do something different whether its through the sites look’s, features or offering a special kind of service that other forums haven’t done yet.
You want your members to return right? Well make them come up ..

Welcome new comers

Always welcome new members, people like to be welcomed. If they find it’s a nice friendly community they will jump into discussion, a good friendship with your members is essential. When welcoming them you can link them to essential topics to start them off e.g. rules announcements or starting points , new members look for help and if you help them they will help your forum grow.
Remind your members
Reminding your members is essential to get some activity back; people often join a forum participate for awhile and then forget about their new forum. Even if your site is unique some people will manage to forget it, luckily for you administrators most forums require an email on signup using this list send out newsletters news etc to anyone who hasn’t visited your forum in awhile, I wouldn’t do this a lot because it may cheese off potential members coming back or put off new members by crowding there email inbox.
Be Active
Members don’t like to see their staff inactive and not participating its essential to spend a lot of time on your forum show passion on your forum subject. Bring in new features discussions etc show that you treat members with respect. Administrators must show that they are active and visible in the community. Members need to know that if they come to problems or questions that they can PM or leave topics and expect feedback soon
Content
Good, unique and fresh content is vital. It is the key for search engine spiders to search your website and return with visitors interested in your topic. Whether it’s a forum post , an article or a guide, the more you have the more information the users will look up on and hopefully stay and become involved in discussion.
When submitting content to various websites an essential key to bring in traffic is
Digg is a place for people to discover and share content from anywhere on the web. From the biggest online destinations to the most obscure blog, Digg surfaces the best stuff as voted on by our users. You won’t find editors at Digg — we’re here to provide a place where people can collectively determine the value of content and we’re changing the way people consume information online. Quoted from ‘ digg.com’