I am not going to get into a whole lot about this subject as it is pretty easy to easy to get started.
1. Find forums in your niche
2. Read some of the back posts and see who is the boss, who post goo content and what the rules are,
3. Start posting with informative information and include you little newsletter byline at the end of your or signature file.
What most people have a problem with is not writing good posts, but finding the forums to post in.
Now that work is done for you. Just enter the topic your newsletter is on into the website below and you will find all the forums you could possibly want on those subjects.
Or go to BotSurfer.com to get your own free desktop multi-forum search tool. What is so great about Bot Surfer is once you find your favourite forums, all you have to do is load them into BotSurfer (up to 15 URLs) and it will surf your favourite forums by the keywords you put into it. It is a great tool, there is nothing else like it – and it is free.