if you want traffic, make sure your site has value and promote it.
a lot of people are only annoyed by adds they see on pages for unrelated sites, so whether it really is worth paying a lot for those...
Even then, no matter how many people visit your page: if it's not what they expect, or if it doesn't provide what they look for, you'll lose the chance for what you actually want: repeat visitors.
This is so true. Your content must be relevant, informative and helpful. You need to be niche specific and you need to provide value. Because of great content people will read your blog and come back to it, no matter the ad.