Help me back up!?

I have just gotten out of a 3 year relationship that I was over a year before I left. I want to be able to talk to girls but I can't ever find the nerve to do it. Ladies, when is the best time to approach you? I just always think, "she prolly has a bf, she's prolly busy, this and that." And what do I say because I have a hard time talking at first but I hate being lonely man it sux, I couldn't my ex cuz she was just nutz, and I really would like to find a decent relationship with a nice girl. NOT a fling or one nighter.