How do I make money off a blog?

What are all the strategies to make money off a blog? I’m thinking of using Googles Blog Spot/Blogger whatever it is called these days!

I’m familiar with adaware from Google… But how do I make more money off of ads? Do I go to relevant companies and e-mail them explaining what I do and how much traffic I get and if they’d like an ad space I can provide the space and they just pay a certain rate?

Thanks guys. Please send sources and what not. I will be forever grateful. I have time to blog, I’m unemployed, looking to employ myself!