For instance, you have a lot of empty boards. You need to fill them with good info relating the the subject of those boards.
That is the most important info I can give you. No matter how good your site looks, if you do not have enough relevant info to keep people coming back you are fighting a losing battle. Having a site that looks good may get people there but the internet is all about information. You must provide GOOD info that people will want as well as keeping it updated regularly. This will depend on the site you are trying to create as well as the people you are trying to attract to your site.
For instance, if you go to a site that says it is about cooking and you find only a few recipes and no info on cooking techniques, cookware, seasonal dishes, etc. would you go back? What would you tell everyone else about that site? This is how people will view your site and judge it.
Things like that have very profound impact on your site. You have very little info in the boards such as music, computers, smf and portals, anime, etc. There is a lot going on right now in those areas. You must add those things to your site so people can find that information at your site rather than going to another site for the same info.
So, you need to think carefully about what topics/subjects you want at your site. You should/will be adding current info all of the time. It is not the job of your members to provide that info, it is yours.
You will also need to make sure things as well written so even a child can understand them and learn from it.
As far as getting people to your site, find someone to create a good sig and avatar. Visit other sites that allow you to post your site there and show off your avatar. People will eventually check it out.