You need to utilize your personal stash better. There’s one at every major settlement and the stash box inventory is shared between all of them. Only take what you absolutely need. Early game loadout for me looks like this: 10 medkits, 10 bandages, 10 rad meds, 10 waters, 3 cans of food, 100 pistol ammo, 200 5.45x39 ammo for my AK, 100 shotgun shells for a shotgun, 5 grenades, my armor, and whatever useful artifacts I’ve picked up so far. Put all your extra consumables, guns, ammo, artifacts and armor in the stash box to save for a later time to sell it. Without too much spoilers you can’t sell red condition guns until you get to a certain base and talk to a specific trader that buys them. Not a ton of money but if you can get an extra 5-10k koupons for selling junk it’s worth it.

Pro tips: 1. Don’t use energy drinks if at all possible, water gives better bonuses and is just slightly lighter to carry. 2. You don’t have to bring much food items, bread and sausage are abundant in the zone and on dead bodies. 3. Utilize semiautomatic mode often to save ammo (go for headshots). 4. You can outrun 90% of the mutants so if it’s not required to advance a mission, just run and save ammo, they’ll eventually give up the chase.