Meeting your boyfriend's friends for the first time can sometimes be more nerve-wracking than meeting his parents. These are the people he hangs out with the most, and their opinion of you will matter to him; therefore, making a good impression is crucial. Being friendly, not hogging your boyfriend's time and treating him with respect will make a major positive impression on his friends, who are sure to let your boyfriend know you're a keeper.
Be outgoing but laid-back. When you meet his friends for the first time, be confident, smile, say "what's up" and just be friendly. Find a way to engage his friends in conversation, perhaps by praising one of them on a recent accomplishment your boyfriend told you about. At the same time, avoid being overly romantic with your boyfriend around them, or you might give them the impression you're the clingy girlfriend who won't let him out of your sight. Instead, make it a point to not just sit by your guy the whole time. Walk around and try to talk at least briefly, one-on-one, with all his friends.
Encourage your boyfriend to make time for his friends. If his "guy time" doesn't change too much now that the two of you are dating, his friends will see you as the cool, independent girlfriend who has a life of her own. Earn more points by suggesting guy time when his friends are around. For example, you might mention that you and your girlfriends went on a snowboarding weekend a few weeks back and that the guys should plan a similar adventure.
Support game days. For guys who are die-hard sports fans, game days are all about gathering around a TV with friends, food and beer. Don't make plans or try to interrupt game days -- this will just make him and his friends resent you. Instead, embrace it as an opportunity to either get into something he loves or enjoy a free day to hang out with your own friends. Either way, making hot wings, dropping off beer or having a pizza delivered will definitely make a good impression on your boyfriend's buddies.
Treat your boyfriend well. The quickest way to turn your boyfriend's friends against you is to treat him with disrespect in front of them. This includes starting an argument in their presence, looking through his cell phone when he goes to the bathroom, putting him down or talking badly about his other friends who are not around. Save grievances for when the two of you are alone. Surprise him with small gifts every once in a while. You can bet he'll be bragging to his friends about you.