There is no magic way to increase...what is your blog. Maybe i can help with ad placement. What is your traffic like? Whats the topic?
Put yourself in your visitor shoes. What will makes you click. For me I'll click when: 1) I'm searching for some info and I couldn't get it from your page. 2) Some ads with catchy wording or interesting image 3) Click my friend's page to show my support . (and the link must be interesting too)