The best way to make money online writing blogs is to post reviews on clickbank products. Choose which products you want to promote that are related to your websites subject/niche, then head on over to the product vendors website to gain as much knowledge as you can about the product. Then write about it in your own words, and at the end of the review place your clickbank affiliate link.
Blogging is a great way to get started; however it can be time consuming. It's best to write about something you enjoy then monetize it with either absence or promoting related affiliate products. Personally I like using Wordpress because you can customize it to look like a real website.
GNHEIL The best way to start making money with blogging is through ghost writing. If you already have a blog, and you love to write, offer to write content on other blogs with linking back to your blog. This would increase the traffic. The main thing about blogs is that they need traffic and constant content creation. Even if you have a product to sell, if the traffic does not convert, you can always add Adsense. But before that, you need to have at least 1000 visitors per day and above to get some "significant value" out of Adsense alone.
Yes i agree with you chris, as you know though, writing new content can be very time consuming, and if your trying to keep up with adding content to your own blogs every day, then you'd soon get overrun posting to other peoples blogs too. If anyone intends to do any kind of writing, whether it be to submit to article directories or blogs, i would advise you to get a good selection of plr articles into your arsenal, and then go through them and rewrite them into your own words to make them unique. In the long run this will save you a great deal of time, and you will not have to do any research before doing so.