Judging by the fact that you posted a question like how to keep him interested here and the way you framed it, I can sense that you are looking for a serious relationship with this man. So, my best advice to you is to just be yourself. It’s no use pretending to be someone you are not just to keep him interested, because even if you do, chances are that he will sense it and lose interest quickly.
It is good to show him all the good things about you, but don’t be desperate to hide all the bad. Eventually, he’ll find out about them so it’s good if he sees them first hand from you instead of hearing about them from your friends. Remember, you really like this guy and wants to be in a relationship with him, not just a one night stand, so never pretend to be what you are not.