Is it smart to scrap most of stuff , or would you sell some?
I'd say it depends on what sort of item we are talking about. In general I would look to scrap junk and sell excess chems. For weapons I would scrap those you may want to use and therefore want to craft and modify. If you never plan to use that sort of thing then you can just sell it.
If you don't have 1st subscription then you'd want to have a limit on what you are scrapping so you don't run out of room. Like you probably don't need to sit on 2500 steel. Just have reasonable limits to cover the sort of stuff you want to build and then stop picking it up, or sell what you do pick up.
I've made a lot of money off chems. I use Traveling Pharmacy to keep the weight manageable, and then sell them with Hard Bargain. Chems are everywhere and sell for a decent amount. You can make a lot this way. Stimpaks and Super Stimpaks especially. Stimpaks are a very common reward, and are also found everywhere, so snap 'em all up and sell them when you have 30 or 40 more than you need. That's a few hundreds caps right there.
Build a water purifier and sell the water. Have a vendor to sell what you don't want like known plans, extra ammo and fuel, interesting or unique items you don't want. But keep in mind that everything in your vendor is still in your stash as far as weight in concerned.
Legendary weapons and armor should be scrip'd at the legendary machines. But if you're short on cash then maybe sell some.
To achieve anything in this game you must be prepared to dabble in the boundary of disaster — Stirling Moss
