1. Respect her mirror space.
You watch yourself to make sure your technique is just right, so why isn't important for her to watch her technique as well? In other words, don't stand in front of her during a set when you could stand just about anywhere else. Just because she doesn't grunt or curl 50lb. dumbells doesn't mean she's not taking her workout just as seriously as you're taking yours.
2. Quit ogling.
If you're looking at her continuously for more than 3.25 seconds, you're ogling. Fortunately, most of you are decent or discreet enough not to do it and you realise that ogling is a form of harassment. For the few that still dare to stare, she is only going to think that you're either a freak or you're desperate--maybe both.
3. If she wants your help, she'll ask for it.
She knows what she's doing and if she didn't know what she was doing, she probably wouldn't do it, or she would ask someone for help. So don't come prancing over with your puny pecs and bite-size biceps thinking that you can bestow some knowledge on how to bench press. Would you do that to a guy? So why do it to a girl?
4. If you sweat, then wipe.
5. Don't speed up when she's trying to pass you on the track.
That just makes you look even more insecure than you already are.
6. Mirrors tell all.
She can see you looking at her in the mirror buddy, be a little smoother than that.
7. The smile rule.
The gym can still be a place to meet stellar gals. You just have to proceed with caution. If she doesn't mind you approaching her, she'll let you know. Just wait for her to smile at you. If she doesn't smile, then don't approach. If she does smile, then stop being so shy, not every woman is self-conscious about her body and doesn't want to ever talk to a guy at the gym.
8. No gum in the water fountain.
You're sweating and thirsty and need to rehydrate and as you take a sip of nice ice cold water, there it is. Eeeeew. Who does that anyway? Gum goes in a garbage can, not in a water fountain.
9. Don't ask her to spot you on squats.