Naughty Ninja said:Next time you see her you can just say something funny if you know she's checking you out. Like: "I lift things up and put them down." in that dudes voice from the gym commercial. She's most likely seen it and will start laughing with you then just ask her her name and give yours and go from there.
I was in the gym once and this girl was working out with a trainer near me. I knew she was looking so I said out loud to myself while benching: "Help me baby Jesus!" and she started laughing. After I finished I told the trainer out loud: "Ask her if she's impressed." and she started laughing even more. Then I just went and said hello and BS'd from there.
This is great stuff.