Just join one that is hosted locally to you, that way you get better ping. (I live on the East Coast and find Dummiesman's East Coast servers to be perfect for me, with only ~20ms latency!) If you're worried about a server or map that you want to join not being populated, just join and within a couple minutes people will start trickling in- once two or three people join everyone else soon follows. Also, there's a voice chat that you can turn on by assigning a key in the ingame keybind menu, but nobody seems to use it for some reason. Enjoy!