First you queue for random battleground. Then you queue for 2v2 skirmish. When random BG pops take the queue and check if you want to be in the battleground.
If you do not,you take the skirmish queue and get the hell out. If you want the ability to leave half way through if it's a bad game,queue for 3v3 or 5v5 skirmish.
Sorry if this a repost