I've heard a lot of Proxy servers are actually bogus and exist primarily for hackers to gain you login details or worse.

There is one very effective way, but you need some experience with PCs. Install Tor (TheOnionRouter) on your system, and the IP address you show won't be your own.

Another, easier, way is to visit a site like Anonymizer before you post your message. These web pages send your connection through a series of proxies (safe, in this case) that obfuscate your address.

Please don't believe people like Pfo further down who say it can't be done; I do it daily.

you can't you can try to purchase a program that says it will use a proxy but as you said you don't know who you can trust with your IP address. the best thing to do in a blog is not give any personal info about yourself such as name or residence and keep comments legal,like no threatening the president (lol). but yes people can abnd will track your IP address as there are alot of wierdo's on the net.

You can try some of these softwares. They are compatible with web browsers like Internet Explorer, Firefox, Netscape etc.

http://www.maskmyip.com/

http://www.proxyblind.org/

http://www.hide-ip-soft.com/ (free trial)