Free ways to Advertise/Promote
1. Use your members! Dont be afraid to ask them to help get the word out. Make a topic in a popular part of the site and give them some ideas how they can help. Ask them to also suggest other ideas. Your members are a great source for the best type of advertising, word of mouth. If they like your site, they will not mind helping.
2. Social Networking sites are a great way to advertise for free. Do you have facebook/myspace/bebo etc? If so add your banner, add a link, add a description, its your profile and you can use it how you like. (dont forget to ask members to do this too!)
3. MSN. See that little space under your name for a personal message? add your sites link to it and ask your members to as well.
4. Find other sites with a similar theme to yours. If members on there have things like facebook or msn, add them to yours. Spend a little time chatting with them, then invite them to your forum. DONT just add them and spam them. This is because they will know thats the only reason you added them and it will give you a bad reputation.
5. Free Ads sites, Classified sites and Ebay. There are a good few free ads/classifed sites out there. Try putting a free ad up about your forum in the category most suited to it. Sometimes ads get pulled, sometimes they dont. With ebay, if you sell on there, add a link to your website in your listing. You can ask members to do this too.
6. Link Exchanging. Add your URL to as many sites with your theme as possible. Supposing you had a music themed site, you could try typing in Google: Add Url Music. It will help find link exchnage pages more suited to your theme. I actually asked one of my members to do this for me, and everyday she is adding my URL to link exchange pages.
7. Signature and Email Advertising. Add your link to your signature wherever you can on the net, as long as it isnt breaking any rules. Even if the site you are on is not particularly about the theme of your own site, add it any way, you never know! You can also add a signature to your emails, set it to add the signature to every email you sent out.
8. Submitting your site to google/yahoo/msn/ask etc. Submitting your site for the most is free to search engines. However it can take a lot of time for it to appear up in the listings so be patient.
Paid Advertising
1. Business Cards/Leaflets/Posters/Car Stickers. These all cost money though how much depends on the deals you get. For business cards, www.vistaprint.co.uk offers you 250 free business cards, with only the postage needing paid. For the poster you can make this yourself if you have a graphics program, or ask someone whom does to make it, then add it to your forum so members can print it off. Send all these out to members whom would like some, and give them an idea where to put them, which would be any places that target the sort of people whom would be interested in your site.
2. Google Ad Words/Yahoo Advertising. This is sponsored advertising which appears above google/yahoo search results ofr to the side. You can set your budget and customize your ads, but be careful, your keywords are very important, choose them well, or your ad will not work so well.
3. Advertising on sites with a similar theme. Some of the bigger sites with a theme like yours will have paid advertising available on their site. This can sometimes be quite worth while. For example i advertised on another parenting site like mine. It cost me £8 for one month, and my feedback showed it got me over 50 members.
All these ways should hopefully get some new traffic coming to your site. But forum promoting is not a 2 week job, you should aim to spend some of each day on your forum promoting it. If you dont have that sort of time, i would suggest asking if there is a member whom would like to be a forum promoter for your site.
Remember, word of mouth is still your biggest form of advertising, so keep your site as trouble free as you can, avoid doing anything that will give it a bad reputation and be patient. It will grow, as more people find it.