Boyfriends want their girlfriends to show support for their dreams, encourage them during times of despair, and show emotional maturity as individuals and in the relationship. It's important that you stick by your boyfriend even when you don't always agree with the choices he makes in life or the annoying but minor bad habits he has. This doesn't mean you don't offer constructive criticism, but you should show patience and compassion when necessary.
Surprise him with his favorite things. If your boyfriend told you he's been saving up for a pair of his favorite brand of tennis shoes, surprise him with the shoes. It lets him know that you're attentive to his needs and that you want to please him.
Don't be too clingy. Your boyfriend will want to be with his friends and family sometimes, and it doesn't always mean it's because he doesn't enjoy his time with you. Send him a nice text message or a written letter occasionally, but make sure he has his space. Otherwise you will appear immature and needy.
Apologize when necessary. Sometimes you may be in the wrong during conflict in the relationship, and the mature thing to do is admit your mistakes and seek ways to work out the problem.
Seek ways to help him improve. If your boyfriend has a hard time with showing affection but wants to start doing it, show more affection towards him. In time he'll slowly make improvements in this area. Also tell him that you would like for him to show more affection and explain how this could keep your relationship interesting.
Tell him how much you appreciate him. Mention that you're thankful for the times he picks you up from work during emergencies or the times when he sends you funny text messages throughout the day. Talk about his physical features that you like or the way he dresses when going out.