This method can be used without having to have your own web site. The major players in the free blog market are; www.wordpress.com www.blogger.com http://home.live.com/ http://360.yahoo.com
There is a list of over 40 hosted blog sites on this page here http://mashable.com/2007/08/06/free-blog-hosts/
There can be problems with having a hosted blog, as you the blogger may not have a lot of control over the site.
Terms and conditions may make it impossible for you to run your own advertising. A lot of hosted blogs do not allow any kind of affiliate links from their sites.

You are also at the complete mercy of the blog hosting provider if they suddenly decide to ban something and your blog contains that kind of content, then overnight, your blog could be gone!
There are horror stories all over the net about this happening to other people.
With a hosted blog there is also the problem that should you decide at a later date to move your blog, you may not have access to all the work you have created and may have to start from the beginning again, although wordpress.com does now allow you to download an xml file so you can replicate your blog on your own hosting space.
Should you choose to use a hosted blog service, I’ll remind you again, do take the time to read their rules and ensure that you comply with them otherwise you are in danger of waking up one morning and finding that you no longer have a blog and if you were trying to earn money with your blog, it will be even worse because if the blog is gone, so is your source of income.
By now you should be seriously thinking of acquiring a web site (domain name) and somewhere to create a site. (i.e. hosting)
Building your own blog is the quickest and easiest way of getting your own site online. When you have your own blog installed on your own hosting account, you can do whatever you want, as long as you don’t break the law 😉 nowadays with the automatic installers provided by most hosting companies, you won’t even need a programmer to install a basic blog for you.

If you need a step by step guide on how to set up and install your own WordPress Blog, I’d recommend you grab yourself a copy of this guide located here http://www.24hourwordpessguru.com
Since that book was published quite a few new themes have been released a really good one is the easy theme, simply because it is easy to install, and use and offers marketers a great theme to work from.
You can grab yourself a free copy either by clicking on the above image or clicking this link here - Eazy Theme For Free.
The Eazy theme for free is just as good as some of the higher priced optimized themes.
Some of the paid for themes will set you back upwards of $47 to use on one site only, however The Eazy Theme really is free. So grab a copy from the link above.
Another theme worthy of a mention is:
The Blog4Cash theme has been developed specifically for Internet Marketers too as a paid for theme, the price is within reach of most people at just $10.00 Take a look at the theme here  Blog4Cash the $10 price is a special limited introductory price, the usual theme price is $49.95

Using a specialized theme will make your blog set up time a lot faster and you will be able to earn money a lot quicker by using either of the two themes I have recommended.
Once you have set up your blog and chosen theme on your own hosting you will then be free to promote whatever you would like. There are no restrictions you have the right to decide how to monetize your blog. You will of course need some capital to do this; you will need to register a domain name and find some affordable hosting for it.
So what do you blog about? The quick answer is anything you like it really is as simple as that. Don’t be tempted to go for a subject you know nothing about or you will soon be found out.
There are so many blogs out there covering all sorts of topics, that no one can tell you what you should be blogging about. You decide and just get blogging, you could just simply have a personal blog, a funny blog, a political blog, a review blog, and there are some really weird blogs out there.
Google likes blogs and does tend to index them very quickly.