You may want to try Google Adwords if you have the money. It takes a while to get established in this business. Posting on forums like you are doing is a good start. Look for cheap advertising for your banners on other forum web sites.

The more time your web site is live the better you will do. People look at how long you have been in business.

It is going to be harder nowdays as web hosting is getting sold for peanuts.