Before I start, let me tell you a little about myself. I personally manage a mid traffic website which makes a decent amount of money. (Overall about 4$ CPM ). I am in partnership on a couple of forums which have heavy traffic and make about twice as much as my solo site. I also have some amount of stake in a few blogs which give a decent return. All my sites are either on VBulletin or Wordpress. I would love to use Xenforo, and I will tell anyone that it's on route to become the best forum system out there. I am prevented by a total scarcity of time on starting a new forum with Xenforo but hopefully soon.
So now that is out of way, let me place my ideas about how you can make money with your website.
First, there are two ways of making money from a site, one, by making a site for the ads and two, making a site for real people. The difference between the two is in scalability. You can make a site in a decently paying niche just for the sake of money and if you are skilled enough and know what you are doing, you can make a decent return but your pageviews will always be limited to the amount of people you can push, eventually after a level, organic visitors won't arrive and a push will become incrementally costlier. Hence your made for ads site will make money, but growing it beyond a certain number of dollars will prove impossible.
The second, and my favorite way for making money is by making a site for real people, which is useful for them and for you and which has the potential to make you a large sum of money which is scalable month on month.
There are a lot of advanced topics I can get into. But I will stick here to the basics. Maybe later, if there is sufficient interest, I can elaborate.. So here goes...