Stay Queued
There’s an additional 200 XP up for grabs for each consecutive match played. This requires staying queued in a single match lobby without backing out to the menu. As you play match after match, win or lose, you’ll earn an extra 200 XP for just sticking around. Joining a match in progress offers an extra 400 XP, most likely because you’ll end up on a team that lost players and is falling behind. However, you can’t control whether you queue into a match in progress, so don’t rely on this for fast XP gain.