In the FAQ, when I refer to light weapons, I am talking about the bray pistol, stormtrooper rifle, crossbolt and the repeater gun.
Heavy weapons are the railgun and concussion rifle.
The tips here are mostly for multiplaying. This goes for both light and heavy fire. When strafing, your opponent will have a harder time trying to hit you. Otherwise you'll risk being hit by the opponents previous shots. Without it, you'll be a sitting duck.