How to earn money through blog

Blogging has become a easy way of earning money..A blogger can earn easily earn 500$/month with less traffic to his site/blog.One of the easiest way is
Publishing Ads..
GOOGLE ADSENSE
It has been paying out at a higher rates..I think its the fastest way to raise your income.One demerit,is that it bans the users abruptly.But there are still kontera contextual ads,Textlink-Ads,Adbrite,Tribal Fusion,ShoppingAds and many more..
Sign Up

PAYPERPLAY
A audio based ad network is popularly emerging..They provide affiliate and referral services too..You need not click or do anything,whenever a page is loaded,you will be paid..
Sign Up

Reviews
If you are good at reviewing products,then you can earn well using PayPerPost and ReviewMe services..PayPerPost demands your blog to be 30 days old and must contain minimum of 10 posts..They pay you from 5USD to 100USD for each review.
Sign up for PayPerPost
Sign up for ReviewMe


Apart from these,you have affiliate programs..Affiliate programs are provided by Amazon.com which hosts the best..I have not tried it yet..
You can even speak up with your local advertisers to setup directly their ads..