There are several simple things guys can do in order to get their point across that they are interested in a girl. Showing subtle hints, along with making sure that the girl is comfortable and having fun, is one key to your success.

One thing that I used to do that was wrong was give off mix signals, the reason was simple, I did not want to give the game away, but by doing this I lost out a lot

One of the easiest things a guy can do is to make the girl talk about herself. This comes in handy in other situations besides the dating world-- all people, not just women, like to talk about themselves.

Ask the girl questions about her life-- what she does for a living, if she has any pets, what type of hobbies, movies, or music she's into. Eventually, chances are you will hit common ground and have a more natural conversation. Once natural conversation begins, interest increases.

Also, be careful not to invade a girl's personal space-- acting slightly aloof, like you are going to leave at any moment, helps pique the girl's interest. If she believes that all your attention isn't focused on her, then she will be more likely to try harder to make you focus on her.

Again be careful here, never get too aloof or she may think your not interested and as a result do what we would all naturally do and give up trying.

Saying things like, "I'm just waiting for my friends here" or "Have you seen a guy with a plaid shirt on?" makes it seem like you didn't stop to talk to her and that you aren't going to go out of your way to get her interest.

Simply put, never ask personal questions, instead ask open ended questions that put neither one of you on the spot. Keep your body language open and let her be herself as much as you can and then her interest will peak.