The settlements will eventually attract people to make:
Food (handy on it's own). Corn + mutfruit (with water) also becomes a stupidly quick/easy source for adhesives. Check the cooking menu, "utility". I'd suggest you try and move settlements over to growing these where you can help it. Adhesives have stopped being a problem for me. Just need a good source for screws now. Anyone spotted a good area? "Robco fan manufacturing" or "deck chairs 'r us" would be appreciated
There's a scrap "desk" as well that (I think) once you have more people can have someone assigned to it to find you screws/oil/etc directly. Oh and shops. I think you put down a frame, the "shops" are then just an alternative doorframe. Having easy places to sell bagloads of loot is definitely a positive.
REALLY do recommend turning up to hard, they aren't everywhere but I get about 1 legendary per quest (either encountered while traveling or one of the beasties related to a quest). Had weapons with some rather unique abilities show up my current 10mm has fire causing bullets.
As a suggestion, make one of the settlements "home" and throw all your junk into the crafting stations there (junk is shared by all crafting stations in the same settlement). When you upgrade weapons, keep a full set of the "base" level mods (standard receiver, basic grip etc) so that when you get an uberweapon you can strip all the mods off your current of the same type to rebuild the uber without having to waste screws/adhesives/oils making the base level mods.
I had a 10mm with powerful receiver, ported long barrel, compensator, extended mags and marksman grip (so almost a fully pimped 10mm), then I picked up the 10mm with fire as a bonus. Had to waste about 6 screws+7 adhesives getting all the good parts off my weapon to put on the bonus fire one... kinda annoying.
The basic mods sell for nothing (like 3-9caps) so just keep em in the craft station pool.
Question of my own: anyone where to reliably find a doctor? Had to abuse psycho a bit in the odd place to give the shotgun enough stopping power when I had something (legendary) in my face. Bit of an addiction problem now and less carrying capacity is ALWAYS a pain in the butt.