Speaking of ranges, it is helpful to get familiar with what ranges a weapon is most effectively used at. A classic example would be the SMG versus the AK. The one weapon having a faster rate of fire means that it can outperform the AK when at short range. Even at longer ranges, tagging an opponent and stripping away one or more ticks of armour can afford you advantage.
A poke weapon like a magnum is most effective at longer range while a scatter weapon like a shotgun can do a lot of damage up-close.
Different weapons work better for different scenarios, and you can use your movement to help manage the range of your engagement. Just keep in mind that in a pursuit situation the defender tends to have advantage.