forums 

Being active on industry web forums will help you to keep up to date with industry goings on. You can discuss with likeminded people where the best margins are, which products are doing well and how to anticipate and avoid problems. Staying ahead of the curve in your field will give your business a far greater chance of success.

You can also seek the advice from people running similar businesses who might have been in the game longer than yourself and who may have insights and perspectives that you hadn't considered.

Don't neglect consumer forums either: they are full of enthusiastic and opinionated customers and potential customers who may be able to tell you exactly what they want and offer honest, direct feedback on your products and marketing.

Knowing your customer is of utmost importance, and there's no better way than conversing directly with them. You may even be able to attract new customers and influence purchasing decisions of entire forum communities if your product and your sales patter is good enough.

Try to be friendly on forums, don't take criticism too personally and never type in anger. It is much better to big up your own products rather than slandering those of your competitors.