I'll arrange to meet a mate at a bar for a drink. I always like to arrive a bit earlier and, often get talking to a lady at the bar. Best of both worlds.Only talk to the hired guns in banter. Nothing too deep. As for others, I always find it weird when some guy by himself tries to join my group at a venue. We often blow him off and I find that to be the typical case. At least in the U.S.
IMO, unless you're a regular somewhere, you should always be going out with at least one other person. This ensures that you can focus on having fun instead of pulling and that you're not viewed as some sort of social outcast who didn't have a single friend to go out with.