Understand that traders visit the forums to get information that will help grow their port, and to discuss movies - in that order. The more valuable information you post, the more people will value your contributions. If posters don't value your posts, then you're probably not posting anything of value. So learn about HSX and the rules about posting. If you want to post news, these columns about posting news and tagging will help you. Think about whether news is valuable before you post it to the boards. If other posters give advice about how you could be doing these things better, please listen to them. And if you're not interested in posting news, join in the conversation, even if it is just saying what you think about this week's openers, or rating the movies you saw over the weekend.
It's an internet forum, and normal internet etiquette rules apply. Treat other posters the way you would like to be treated. Don't write in all caps, because no one likes the ALL CAPS GUY. Don't spam the boards, because it makes you look like you never think anything you don't say.
Keep in mind that things said on the boards are usually not personal. Posters want to be first with the news, or they want to be right, or they want to be funny, or they just want the forums to be a better place to visit. It's only personal if you take it personally.
Remember that it is a public forum, and that everyone - not just the person you are posting to - can see what you are posting about. It's very easy to win an argument with one poster, and at the same time lose your reputation with the rest of the community. Also, try not to share more about your personal life than you have to. Some people find that soft underbelly is delicious.
Please don't feed the trolls. It can provide some entertainment for the larger group, but it gets old very quickly and it's usually not worth it. And when things get to the flame war stage, don't perpetuate it, just walk away.
Finally, remember that it can take time for an internet community to accept you, but if you post interesting things and are generally pleasant, you shouldn't have any problems.