A lot of forums have specific threads designated for welcoming new members, where those who have just registered are encouraged to introduce themselves. Your introductory post should basically inform the other members who you are and why you’ve joined the forum. The reason you give should not be in any way business-oriented. Making a sales-pitch in your first post will definitely be frowned on and may get you banned.
Do not post immediately. Most forums have at least one, large, close-knit community in it. If you suddenly post on a thread where discussions have been carried on for days, you shall be shunned and ignored. Spend some time going through the archives?figure out which topics are perennial favorites and which users are the unofficial leaders. Also observe the particular etiquette of the forum.
Whenever there are questions asked that fall within your area of expertise, answer them to the best of your ability. Back up your answers by providing links to trusted sources and answer follow-up questions promptly. If you prove to be a helpful, efficient member, you’re more likely to be paid attention to.
Do not get involved in heated arguments, no matter what you think of the question at hand. Keep reminding yourself that you’re there to build up a clientele for your business; stay away from topics like religion, race and politics; don’t immediately respond to criticism; make sure the others know when you’re joking; leave discussions when they become contentious.
Once you’re acknowledged as a respected user, start marketing your products aggressively. Focus on techniques which are likely to prove beneficial to the community as a whole. Offer forum members free samples and/or discounts. However, make sure to obtain the forum moderator’s permission before you start a marketing campaign.
If you are hiring a marketing agency to run your campaign for you, research their methods. A lot of agencies use robots to spam forums. While spamming might ensure temporary traffic, in the long run, it’ll do you more harm than good. Forum users dislike being flooded with spam and can blacken your reputation if they so wish. So accept the services of only those marketing agencies which will abide by the guidelines set out above.
If at all possible, you should handle your own forum marketing.