I don't know really how it happens. It looks like the older the blog is the more traffic gets. Maybe it's because there are more entries already in the blog. The blog topics happen to be interesting and many online surfers are into the topic. I started blogging because somebody told me it was interesting. Then I learned of how to make money out of your blog. The principle is simple really. The blog if visited frequently is a good site to promote anything. So what you do next is look for advertisers. Almost everybody knows off ad sense. If you haven't heard of ad sense yet I don't think blogging is for you. Ad sense is one company called ad aggregator and there are other ad aggregator companies you can look for online. I'm sure you have seen some of them on pages you have visited. If you have enough traffic on your blog you may even qualify to write about products or companies that will pay good money for your review. They will pay you for the arcticle and so they can post it on their web sites or just pay you good money for writing about them on your personal web site .
Some ad aggregator companies will not allow other companies to have similar ads on the same page that carries their advertisements, in this case you can alternate pages for different ad aggregator companies advertisements. Or you can just totally do another web site for each of ad aggregator company that you have this way you can have several web sites and several ad aggregator companies working for you.
You can also increased traffic your web site by advertising your own web site. You have to pay minimal amount for a possibility of increasing your traffic thereby increasing your traffic income.