Do you want people to miss you when you're gone and to be excited when you're back? Do you want to be able to claim that you helped FWG gain another 3 members today? All you have to do is practice polite conversationalism. That is, be a fun and considerate person to talk to.
The most important and the simplest rule to follow is just to ask the other person about themselves. People love talking about their day, their pets, their interests; reach out to other chatters and express interest in what they love. In addition to the possibility of you learning something new and interesting, you'll also garner appreciation and a reputation as a really nice fellow. Be sure to be genuine, however; over-zealous and obviously constructed interest in others can lead to the other person being bored of talking about themselves or you gaining a reputation as insincere.
NO:

YES:

Beyond that, any supplemental advice I could give would be based around putting yourself in the other chatters' shoes. Would I like someone who only pops in every 4 minutes to complain about something or leave a single message about a topic only they enjoy? Probably not.
Remember folks, a healthy and fulfilling conversation is full of give and take. Don't hog a conversation talking about yourself and remember to leave opportunities for others to ask questions or make statements of their own. Don't forget, this advice is also very applicable out there in the real world, guys. Thanks for reading!