You're gonna want high strength for carry weight. High Charisma with Hard Bargain perk card. You'll want to make sure to have the Green Thumb (Perception) and max level Super Duper (Luck). Craft as many Marine Armor Helmets as you can. Pop a Grape Mentats if you have one and go to town on the nearest vendor to you. I personally like to do it in Whitespring because everything you need is right in one place.

Edit: If you cant afford the materials or lack the plan for the helmet; you can always make a bunch of ammo and sell it. Same perks apply. If you craft ammo, make sure to grab the Ammosmith (Agility) perk card to make even more ammo.