It is always a smart thing to have a plan for how you want to tackle things in business and this also means forum marketing. You will not have any problems with reaching your goals, but you should know what they are and how forums can help you. Successful marketers get that way by using this train of thought. First, they take the time and learn about various marketing methods. Then this information is tweaked to find the best outcome.
The majority of people will not change their usual personality when joining a forum. Most people are going to be either aggressive or shy. So, just act normally, unless you are very aggressive and obnoxious. if you are not that outgoing, don't feel pressured to talk on the forum just yet. This behavior is called lurking and lots of people do it all the time. It can feel a little daunting to make your first post, and it's a lot like being in a new city or town and going to a new school. Once you settle into it, then simply start replying in threads and always be courteous and offer value.
One quick and easy way to get an idea if marketing is allowed in a forum is to look for signatures. Find out if the signatures have links. This is the usual practice by forums if they don't mind members placing their business links in their signatures. After you have seen many forums, you will be able to tell what to do in terms of forum marketing rules. Plus you can also get better ideas about what is allowed by taking note of other things in signatures. For example, they could possibly have a lot of links and a few graphics. This will tell you whether or not marketing is really allowed.
In line with other comments about how you conduct yourself, or the attitude you create, you have to just be relaxed and cool in forums. When you go to the forums, you will form relationships with many people. Some people will always come off as arrogant. You'll see folks who are habitually Going Here negative and complain a lot. A majority of member will ignore these people, which will make them drop out of sight. These are the unwritten rules of forum marketing. So you have to determine what is important to you. If you want to successfully market in forums, then you have to adjust if that is necessary.
I've seen very many people become addicted to hanging out in forums. Try to keep your thoughts focused on why you're there. Don't lose sight of the value your time has and where it would be wisest to invest it. That's what you have to do if you want to make the most of your time.