This Times for real,
If you are going to be nervous and desperatly try to make them laugh then they probably will not laugh because you will not be projecting it in a funny way. About feeling bad because other girls already like you: are you prepared to go out with every girl who likes you? Why is it your duty, just because they like you, to make sure they don't see you DJing any other girls?
You should not be focusing on girls feelings/what they want its all about what you want and your feelings. You should stop focusing on the girls, if you do everything you can to make yourself happy then you will be interesting/funny/confident because thats what all the guys who really look after theirselves are. "How do I keep her interested?" is not the question you should be asking it's "Is she making me interested enough/Am I having enough fun" Putting her feelings/fun first is AFC and why AFCs don't get many girlfriends because they don't even think about how they are feeling.