The 'Action' key - E on the PC - instantly completes all terminal screens so you don't have to watch the stupid teletype animation of it filling one character at a time.
You need to assign settlers to most jobs in a settlement - scavenger benches, food, guard turrets - to get benefits of them. Do this in Workshop mode by selecting them with the action key (text will turn to Assign) and then click on the thing you want them to do. You can also assign settlers to their own beds using this method so they won't sleep anywhere else.
Change settler's weapons and armor for better stuff! When you're trading with them there is a key to Equip (T on the PC). They need just one unit of ammo for the weapon you give them. You often cannot see a settler's clothes in the inventory. That's okay, just equip something else and their useless clothes will appear so you can take and scrap them
Change Mama Murphy's clothes BEFORE you build her a chair or you will never be able to do so again.
You can Favorite/hotkey food and drugs, not just weapons
When you modify weapons and armor, store all the old mods in the workbench. This prevents you from having to build "unnecessary" basic mods (wasting materials) when switching mods around between items.
Pre-war money is worth much more in trade than as cloth. Since the workbench will automatically scrap it when you build stuff, you will need to manually segregate it into a container that YOU built. Cigarettes - single, packs and cartons - and gold watches are the same.
Take the Fusion core out of any Power Armor you're not wearing to stop settlers or raiders from stealing it.
Never trust a container for storage that you did not make yourself. Pre-made one can and WILL reset back to their default contents and you will lose all your stuff. There are a few exceptions to this, but I find it easier just to not trust anything rather than trying to remember the exceptions.
The stimpack animation time has caused many a death. If you're about to die, take Jet first (hot key it) then use the time slowdown to take your stimpack(s).
If you get the glitch where a gun doesn't switch properly to another one, quickly changing to third person view and back often fixes it.