Since I work all day, I don't get to the gym until 10pm at night. Every Monday and Wednesday I see this same HB at night.

She is single, because I saw a profile on match.com.

How do I open or engage in conversation without appearing to be creepy?

Last night she was on a machine talking to a guy/friend. As I walked by, she stopped looking at the guy talking to her, and we made eye contact. I gave her a smirky kind of smile, and she smiled back as i walked by to head out....

How to approach? What to say? thanks

"soooo... do you come here often? " try to act super smooth and then just as you finished saying it start laughing and follow up with "yeah, i cant pull that off can i?" and a nice smile. the girls i tried it on were both +- my age (20) so i followed up with "anyway, did you see me over there? *point somewhere* i was doing my squat thrusts." this is also done in that exaggerated super smooth voice and tone. she'll laugh and then you just go from there...

i've tried it twice, first time (hb8) the girl was very receptive and in a very good mood... but i didnt have my phone on me so i couldn't #close, so i went out on a limb and invited her to have coffee with me later on during the week. it worked.
2nd time i got a "wow" and then the girl just started laughing and we ended up having lunch the next day.

Well, can't give you too much advice on approaching because I do not know how much attraction you already have built up. But when in conversation:
Definitely don't talk about gym stuff or she is going to think that's all you are about. Also make sure you have a low-commitment plan for yourself in the next couple days (like going to the mall). Say something like "I'm going to the mall tomorrow to pick out shoes and it would be great to get a female opinion. You could tag along if you like."
I wouldn't try to DHV much inside the gym or you will appear full of yourself, but one or two friendly negs would be nice. Good luck. I'd say overcoming your AA and talk to her would be half the battle.

Edit: Yea... I would not do what the post above me said. Even though it's kinda funny, you are giving DLV's and showing insecurities in yourself. This would be OK maybe if you were being spontaneous with a stranger, but if it's with someone you have seen before I wouldn't.

You have thought about it way to much. The fact that you have taken the time to post on the website and ask for an opener shows that you are over thinking it. If you want a pre approved openers they are all over the internet. The main thing you need to do is innitiate conversation with her as soon as possible. The longer you wait and think about it, the shittier your game will be. Just approach her like a normal person. Get it over with and either try to fuck her or move on because the more time you spend thinking about one girl your not banging, the less likeley you are to geyt layed. Good luck