I've only been to the bar alone twice now. Maybe this is obvious to others but I noticed that people are much more likely to talk to you if you actually sit at the bar (the long counter beside the bartender).

I saw girls going up to guys 3 times their age and talking to them. He could've been their grandfather. I was sitting at a table alone and thinking what the hell. Then I noticed that there were tons of people talking to each other up there. They all came separately so they definitely didn't know each other. Guess I'm sitting at the bar next time.