well, you may produce the drug Jet with easy to find raw materials like plastic & fertilizer.
Produce Jetfuel ( jet and flamer ammo), you earn caps and XP
After clearing out a building or campsite make sure to pick up every thing and use dog meat as a pack horse then you can sell and or trade for things like bullets and better armor this early in the game.
If it takes 3 or 4 trips to each site just do it for the long run it helps and pick up every thing.
I have 4 chest that I put every thing in until i need it to sell or scrap for what they have.
Place all junk in the workbench for later use and after you get your settlement fix the way you want it you can use the junk at a new settlement or sell it.
Save up about 500 caps (depending on your Charisma) and buy a shipment of fertilizer from Connie Abernathy. Take that back to Sanctuary and use it to make Jet. Take that Jet back to Connie and use it to trade for the two shipments of fertilizer she stocks. You can repeat this every day or two as she restocks her stores, and when her stock gets limiting, Mr Green at Graygarden also stocks two shipments of fertilizer. You'll have to scavenge plastic to keep this up, but it's easy enough to find.
One caution: Do the math and make sure you're coming out ahead on that Jet for Fertilizer deal. I've never tried it with a really low Charisma, and it's possible you might be losing if you're especially socially awkward.
I have 10 settlements set up with over 200 water production. They I usually pull out over 350 purified waters and can travel the entire Commonwealth and leave them broke. Also the scrounger perk for extra ammo will bankrupt the rest. I never have had to sell legendary or valuable gold (need it to mod settlers weapons). I usually have 50,000 caps and 2,000 pre-war money. The only time I have been broke is after I dump 16 stores in a settlement
Speaking of Pre-War money, has anyone gathered the 5K required to bowl at the bowling alley?
Is that a real thing? Or... WHAT?!
I wonder if that is before you complete the quest there?