It's unfortunately a lot harder to make money blogging than many articles make it sound. There's no magic bullet.

Yes, you usually have audiences who are targetted to a niche, but those readers are there for information - not to buy. Moving them from readers to buyers is no simple feat.

Bloggers, you might make a little cash here and there between google ads and affiliate links, but don't expect to make much more than your annual hosting fees without a lot of time and effort.

I'd say sidebar banner ads are the least effective, while text links embedded in your blog posts can be somewhat effective. But it gets hard to find content that lends itself to embedding links without sounding like you're just advertising a product.