Rule 1: do *not* "express your feelings." That virtually always drives her away, no matter how much people will tell you it's "the right thing to do."
Rule 2: Attraction is NOT a choice. If she's not into you, there's nothing you can do about it. Conversely, if she's into you, there's nothing *she* can do about it
Rule 3: A woman becomes attracted to a man based on the FEELING she gets when she's around you, and when you're not around and she thinks of you.

Your best bet: have *fun* when you're around her, and pull her along into your fun, so to speak. Make her laugh, make her smile, be relaxed, confident, and at ease around her. (Important point: don't use self-depreciating humor. A lot of guys hear that laughter works wonders, and then go on to make fun of themselves, getting lots of laughs as a result, of course, but in the end self-depreciating humor kills attraction just as much as no humor at all).

Be spontaneous! There are few things a woman likes more than a man who's totally unpredictable when it comes to the next adventure. You don't have to be adventurous, of course, but you get my drift. A good idea: watch some romantic comedies and some James Bond movies as well. And watch "Accepted"..Bartleby Gaines is the perfect example of what I'm talking about in the last 3/4 of the movie.

Also: Chivalry isn't dead.

Cheers!
-MarsNS