You can try article marketing at an article submission service like ezinearticles.com and link back to your website in the resource box for your articles. Create a video and upload it to YouTube with your URL flashed on the screen. These can bring many visitors to your site.
Try to exchange more links, submit your site more often to search engines, directories, etc. Always try to 'revolute' your content, try something new, catchy, yet unique. I know this is hard but once you accomplish this you will get visitors which will browse your site and re-visit you later. This way you have higher chances for you advertisements to get clicked.
Content is KING - GA is important. You are able to earn money as soon as your website/blog/forum stand a good amount of traffic. Remember that visitors from google search engine stand more chance to click. Hope it helps