Once you've decided to create your own blog, the first question you have to address is whether you want your blog to be hosted on your own web hosting account or be part of an already established site like wordpress.com, blogger.com, or one of the many other free blogging sites.
If you use one of the free "hosted" blogging sites (Wordpress.com, Blogger.com, LiveJournal.com, Blog.com, and many more) you can create a brand new blog in about 15 minutes. When you choose this option you become part of a larger site such as wordpress.com and your address will be something like
http://yourtownrealestate.wordpress.com
or http://yourtownmoneymanager.blogspot.com
The advantage of this approach is that it is fast and cheap. Plus you will get some traction and search engine exposure for your blog because it will be part of a much larger network that gets crawled by the search engines on a regular basis.
But in my estimation, the disadvantages outweigh the advantages.
Follow up:
First, you cannot use your own domain name on one of these hosted networks. For example, I would not be able to use my own domain, rickhendershot.com at wordpress.com or blogger.com. That means I would not be able to develop my own online identity to its fullest extent as part of a hosted network. That is no big deal if you don't expect to develop your blog into a significant communication channel. But if you do - if you want to get serious about blogging - then you need your own domain, set up on your own hosting account.
Second, when you use a hosted network there are limitations to what you can do. For example, there are design limitations, and there are limitations to the "plug-ins" and "widgets" that you can install. These plugins and widgets usually add functionality to your blog or let you interconnect with blog sharing services like MyBlogLog.com and others. When you host your own domain on your own hosting account you will have access to the full range of these addons.
Third, when you use a hosted network you are at the mercy of the rules and regulations of the specific blogging network you join. For example I recently had a number of blogs shut down by Wordpress.com because they decided they did not measure up to their (pretty vague) terms of service. In my mind these were all legitimate blogs featuring original, useful content, but somebody somewhere decided they were too focused on generating links. No warnings, no recommendations, no recourse or appeals. Just a message page at each address saying: "This blog has been archived or suspended for a violation of our Terms of Service."
That was a lot of work flushed down the drain, and it taught me that free services are not worth much if you want to control your own online destiny.
For these reasons I don't think there is any question that hosting your own blog is the way to go if you want to build your online profile in a serious way. The downside is that it will cost you a few dollars to set it up at the beginning. It will also require a bit of technical know-how to get it running properly.
You will need to buy your own domain name. That will cost you $7-$10 per year. And you will need your own hosting account. That will be somewhere in the $5 - $10 per month range.
But these costs are insignificant compared to the potential value you will be getting from them. Having your own domain hosted on your own web account gives you the ability to create a real web presence - your own online identity. And your blog can serve as your primary communication channel for achieving that goal.

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