1. Sign up for an advertising network, such as Google AdSense or Chitika. You will receive a small amount for every advertisement your blog visitors click on. Some ad networks pay you based on the number of impressions, or times an ad is loaded, not the number of times it is clicked on. Usually, the ads will somehow relate to whatever topic you blog about.
2. Sell ad space directly to companies that are relevant to your blog topic. You will probably have to build up a large following in order for companies buy ads directly from you, but once you have that following, selling ad space direct will make you more money than using cost per click networks.
3. Burn an RSS feed for your blog and place advertisements on it. Some ad networks are designed specifically for feeds while other networks, such as AdSense, will ask if you want to include ads on your feed. RSS ads are a must if you want to earn revenue from people who only read your blog from their RSS reader.
4. Become an affiliate. Certain web retailers, such as Amazon, have affiliate programs. You put a banner on your blog and if someone clicks through it and orders something, you receive a small percentage of the sale as a referral fee. You can also incorporate text links to an affiliate in your blog. For instance, if you are writing about a book, include a link to Amazon in the blog post and you will earn referral fees if someone clicks through.
5. Ask for money on your blog. Directly asking your readers to support your blog may seem cheesy, but can be totally appropriate, especially if you are blogging for a non-profit company or if blogging costs you money. If your readers value the content you provide them and want to see your blog succeed, odds are some of them will donate. You can place a link to Paypal directly on your site or add a donation widget through Wordpress or Blogger.