Get people and advertisment from related sites.
E.g. you are hosting a guitar site, go for music related site for advertisement. Do some link exchange or banner exchange with music forums or guitar stores.
You can even organise a event which is from the management of your site. (as small scale as a school concert to big events).
There are actually alot of ideas which you can use. The most important thing is to get the attention of the right audience.
Hope this might help.
Anyways, you need to create a draw. By the time kids are in high school they should be able to comprehend a forum, so get a few of your friends posting. If you can get a dozen of your friends posting and rack up a few hundred posts (20 or 30 each?) people will be bound to jump into some conversation. Do this to gain more local popularity, then focus on affiliating or getting linked to increase PageRank so you'll be closer to the top in Google.
I have just done the exact same thing, i have just started a guitar site, and i find some of this info useful. I have only had 233 hits this first week, which is not to bad i dont think. But if you want to advertise your site with mine, go to bgsplace.com/sites and it will tell you all about it there. I have been to all kinds of forums posting and advertising. now it is time for this one... bgsplace.com , guitar help,tools,links, and more!
2) Create cool flyers with your website name and purpose
4) Have usefull articles, this will index you in the search engines everytime someone searches for something related to your article.
5) Have a keyword rich website, do your meta-tags, headers, image text. etc
6) Have a feature on the website "tell a friend"
7) Have weekly contests and competitions
I have found a good site to get your guitar site recognized on, you can click the link, and go to the site, and also help me a lot by moving me up the board. The higher you get up the board, the more recognized you get. Here is the link