How to earn money from blogs?

Have heard a lot about people earning a lot of money on blogging, but I don't think it is that easy to make money on it. First you need to find something to blog about so that you have several thousands visitors daily. Then you need to have commercials that they find interesting so they will go and visit them so you can make money. And since many of the people who will visit your blog will come again and again, then you need to have commercials that change very often. Think that the blog and the commercial part is not the biggest problem. Getting people to come and visit your blog is the biggest problem. You have to spend a lot of time to tell about your blog at different places. But if you have a really good blogg then it might get a lot of visitors fast. Do wish you god luck with you blog. Hope you will succeed :-)