1. Be warm when you meet them. Remember that first impressions last. Let your human pheromones exude your natural charm and grace. Be at your best. Smile! To be introduced to them as "the girlfriend" is a great sign as this connotes that he's serious with you; he's putting your relationship to the next level that he wanted his close buddies to like you too. This also means that their opinions matter to him. Just be yourself when that moment comes.
2. Learn to differentiate "friendly" from "too friendly". Know your boundaries. Too much interest to his pals might put you in a bad light. You wouldn't want them to think that you are a flirt, would you? Do not hug or kiss to greet them. Avoid physical contact. No matter how innocent it may be on your part, it could be taken differently either by the person you hugged or kissed or by the people who saw the whole thing.
3. Regard them as you would with your own friend. It's his best guy's birthday this weekend, help your bf pick out a gift. This simple gesture will be much appreciated both by your partner and his friend. It indicates you care enough to exert the time and effort. Join a group hangout. If they have a basketball playoff this Sunday, watch them play. Keep in mind that the way to a man's heart is through his stomach. Thus, use this chance to showcase your culinary skills. Bake your specialty cookies or prepare your finest lasagna. Be sincere when you talk to them. Say only the good things and do not obsess on the bad ones. If you see that one of his mates is a bit overweight, do not add insult to injury and mention the obvious. Respect them as you would do with your girlfriends.
4. Be nice to your sweetheart. It's not unusual that they would initially be apprehensive as they see you as a couple but you can easily erase those doubts by being an ideal gf. Make him feel like he's your hero. Respect his decisions and individuality. Appreciate him. Let him experience the passion and excitement that only pheromone advantage can bring. Give him a reason to brag about you so they'll be interested to get to know you more. Show your emotional maturity. Treat him well. If you behave like a child throwing tantrums in the middle of a fight, he might ask for their advice on how to deal with you. Do not give him that opportunity.
5. Recognize his space. Avoid being clingy and sending text every hour when he's on a Friday night out with his guys. Trust him and understand the word "privacy".