Never reload in the open
You are at your most vulnerable when you’re reloading. You can’t do anything once you hit reload, so it’s possibly the worst thing you can do in the middle of a fight. It’s wise to reload every time you know you have a spare second, and most importantly, when you’re behind cover. There’s nothing worse than running out of bullets when going face to face with an enemy who has a full clip. It’s wise to reload when you’re down to a quarter clip of bullets.
(Tip from Dave Cook)