Demorgan87: I don't really participate in these things so I'm a bit unsure as to how to proceed.
1. You should probably post what you have as well so people know the kind of stuff you've got to offer in return (unless you plan to buy a game in exchange for stuff or something).
2.
BE WARY OF SCAMMERS. This is pretty much the most important tip you can get. As a member who's, as you said, new to this, you're likely to get targeted. If someone approaches you with an offer, be sure to look up their username on the forum. If they have no activity or 90% giveaway activity (as in taking, not giving), you're probably best off avoiding them. It's also worth checking their name against the known scammers list/wiki mentioned on the OP. If in doubt and even the slightest bit suspicious, you can always ask around. The community tends to be pretty friendly and helpful about this.
3. Be sure to list what platforms you're interested in. In other words, do you want your game from Steam? From GOG? If you have games to offer, are they for Steam? For GOG?