As a woman, one of the biggest turn offs in a man is selfishness in the bedroom. Many of us have excitedly hooked up with a new partner, only to be severely disappointed when it comes to sex. This kind of thing happens all the time and will continue to happen multiple times throughout a woman's life. We're not talking about men who lack experience, we're talking about men who simply don't care about pleasing the person they're with.
Always make sure you're looking out for your partner's needs in the bedroom. If you're nervous and feel like you're too inexperienced, ask her what she likes and she'll be more than happy to guide you down the right path. The main thing is that you should care about her pleasure and make efforts to ensure she has a good time, too.