Weapons -
WSTR Combat Shotgun for super close range quarters. Usually 2 shots will do the trick. If you have a weapon chip to increase melee damage after dealing damage, put that on to fly in paired with
Smoke Grenade's to finish off any enemy who might've escaped.
V22 Volt Thrower or
V75 Scar to bring alongside, for UESC and any fights out of shotgun/melee range. Volt ammo is the most frequently dropped ammo and is the easiest to keep up on, just don't reload a lot so you don't waste ammo.
Equipment -
Smoke Grenade, use these to activate your
Shroud and get up close and personal with enemies, whether that's with your melee or shotgun.
Shield/Backpack - Simple, use whatever you have the best of at that time. Ammo backpacks are beneficial for being in lots of combat, so use those if you have one.
Cores -
Ghost Protocol &
Breathing Space, make smokes last longer, and reload quicker in the smoke, best combo for fast shotgun action.
Implants -
Augmented Capacitors V2 provide +20 to Prime Recovery, so Assassin's
Smoke Screen is more readily available.
Knife Fight V1, boosting Melee damage for those fights inside of the smoke, the more melee damage you have, the better.
Strike Kit V2 for boosts to Ability recovery, and Melee damage. Adding in the movement speed buff from breaking a hostile's shield, and they won't be getting away.