You can see that sites like a-ads or some like that related are a good way to earn some BTC advertising in your blog.

You have to search for sites that pay for clicks and views because some of them are only paying for clicks and if you have a lot of visitors but no one clicks in your advertising you dont earn nothing.

In adsense as our forum members told you, you have to wait 6 months or more for join it, but you can start winning money from day one if you search for some one who pay you for articles related with their companies..  but you need do more than just write your blog, you have to call to thoes companies and convence them, if you have a big audience then they will pay you.

So, good look my friend.