Melee
In no circumstance should you ever engage in a melee, whether single player or multiplayer. In the time that it takes for you to recover from the melee, your enemy has time to shoot you. Hand-to-hand combat does little damage and you shouldn’t have to do it; your pistol has unlimited ammo.
Health Regeneration
You do not regenerate health unless you are out of combat.
Headshots
As in most games, headshots do more damage. If you’re comfortable dragging away from the aim assist on your phone, go for it. However, in the heat of a firefight in multiplayer, while getting more damage in faster is always good; if you take too much time breaking out of the aim assist, it may cost you.
Movement Speed
You can move in all directions, but you move significantly faster when facing forward.
Ammo Boxes
Keep an eye out for ammo boxes. They’re the little boxes with a blue-green aura. The ammo boxes refill ammo. In multiplayer, these boxes are on a timer and can be picked up by all players, so be on the lookout to get to them first. Single player is more generous when it comes to the number of ammo boxes that appear.