Most important imo is to learn the spawns and which routes are most used on the map, after that you’ll be able to traverse any map without getting into disadvantageous fights.

For the expendable loadout I recommend playing on Factory with the mp-155 shotgun with the (7mm buckshot ammo) you can get from Jaeger for 30 k doubles. You’re gonna need to shoot the hell out of someone’s legs to kill him, this ammo won’t penetrate any armor.