I need a dating guru!

So, today I had another adventure at the gym. There's this guy (boy, guess you didn't see that coming, eh?;)) who has been coming to the gym for a while. I had never talked to him, but have certainly noticed him. He's pretty quiet, does his thing on the bike for a good, long time, does a hard workout. He's got this tattoo, which I usually don't find attractive. Anyway, I guess he noticed I had been noticing him because a few weeks ago when I was doing one thing on one of the machines, he was on the stationary bike facing me. He nodded and sort of mouthed "hi", to which I nodded back. Since then we usually make eye contact and smile, nothing major. There are a couple machines that I need someone to take the seat out of so I can fit in with my chair. It's always a pain to ask someone to remove them. Anyway, today as I'm on one machine, he comes over and uses the machine next to me. He says something. I had my handy little protection with me (my iPod), so I didn't hear him. I took out the earphones and said "sorry?". He said "I was just saying hi, how are you?" Of course this is where my face inevitably goes red and I get all flustered. I said "Ohh, fine thanks, you?". He nods and we continue to do our workouts. Then he removes the seats of the machines so I can access them without me asking. Except, my back was turned when he did that, so I didn't see him do it, but asked him if he had and he said yes, to which I thanked him. Then I got all self-conscious. And that was it. So now I'm already freaking about the next visit and how I should handle it. I've already made it huge him my head, which I know is my first mistake, but I can't help it! I've probably read too much into things. Now I have days of going through the "should I say hello? Should I seek him out to do so? Do I just smile? What do I say? Will I be an idiot and go all spastic and simply ignore him? Play it too cool? Do I show interest? Do I leave my iPod at home next time? Aaaaaaaah! The doomsdayer in me has already convinced myself that I'll blow it, although there probably wasn't anything to blow in the first place as I've obviously made this into something it isn't. Is there a big fat L on my forehead? Thanks. That's great. Sigh.