Best Opening Line Ever:
I hate the phrase "pick-up line," because it reeks of moronic lameness. But, you have to say something when you're in a situation where you need to say something so you don't look like a tongue-tied cretin. Here's my favorite line, spoken when there's a genuine opportunity or reason to say something to someone who is a stranger to you. It works in all situations, regardless of who you say it to. It's an all-purpose line. Say it with a pleasant expression or a smile:
"Hi, I'm George." (It's probably best if you use your own name, rather than mine, though.)
Then, listen. You have just begun a conversation, and there's no way to know where it's heading. The next thing you say will depend on what you hear as you listen, on the circumstances of the situation, and on any other factor that may be pertinent. For example, if there's a hurricane outside, the weather might be a good subject. If you're at a party, inquire about the hosts of the party and how your new companion knows them. You get the drill. It's a conversation, so converse.
That's it. Play the rest by ear.
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It's so much fun being friendly to strangers. They usually don't expect it. 
Assuming, of course, that you have not spent too much time at the open bar, that is. 
It has changed my life.
I've basically been trying to un-shy myself. It's working extremely well.
Actually, psychologist Richard Wiseman did a study on chat-up lines. He's the author of Quirkology where he delves into speed dating to answer that question. His conclusions were pretty much that anything that gets the other person an opportunity to talk about them self is good. The important issue is to do it in a humorous way.
But a simple introduction might give one an opportunity to do just that.
"I can buy my own damn beer!" Lol 
Especially changing after a swim.
of "Screw off! That seat is taken! 
!" (Not sure why; it seems very endearing the way I deliver it.) But your method may come off as a bit more welcoming...