I was wondering if it's a good idea to build awarness and inform potential customers about your service by starting a discussion(thread) in a niche forum.
Any do's and don'ts you could recommend on how to start such a thread?
The answer depends on the rules of the niche forum. Every forum has its own community and its own rules. What is acceptable in one place will get you booted out of another.
You need to research the rules of the particular niche forum you are considering writing in. If it is acceptable to discuss a service there you need to go about it gently. Newcomers to a forum are often not well respected (no one knows you yet) and starting off on the wrong foot can generate more negative press than you could hope to over come.
I agree with Gary E that being a newcomer will make it more difficult. You may first want to participate and not mention your service for a little while, but develop a reputation as someone who knows what he is talking about.
Then, when you mention your idea, you will have a better idea as to the unspoken rules, and since you are well-thought of then you are more likely to be listened to, rather than being seen as someone that is very annoying.
You can also see if you can contact some people from the forum privately, if possible, with an offer that may help them, but once you make your pitch then let them decide, don't push, the hard sell may not be appreciated.
Once you get some people to try it then they may talk about the service, which gets you off the hook, you can just help explain about it, to answer questions or concerns, without having brought it up.
Developing a positive reputation is always a good idea, especially when the market is fairly small as people may try your service because of what they think of you.
Identify a few bloggers who are particularly influential in your target market segment.
Before you do anything else - stop - and go back and read what they've been posting and what kinds of comments their posts generate.
Build your reputation on the blog by offering thoughtful comments - do not "pitch" your new service. Instead - it's reasonable to ask questions about problems they're having which you think your service will address - so that you get a better understanding of how to position your value proposition.
I agree with James and Gary - don't do the hard sell dance - listen, learn, and gently offer value.
David Meerman Scott has some excellent tactical suggestions on how to interact with bloggers in his book "the New Rules of Marketing and PR". David Meerman Scott's site
You've identified a problem. You wonder if anyone has the same problem and at the same time, may begin to ponder solutions. Maybe you do a search to see other people's opinion on the subject. If you are sincere and want to relate to this niche market, you will do what most do when confronted with a strange place and wish to avoid offending, you listen.