The radroaches in Vault 111 are easy to kill. You can save your ammo.
Idiot Savant can proc during quest completion. If you’ve got a quest that has a huge XP reward, consider save scumming. Save, turn in and wait if it procs. Reload if it doesn’t. Repeat until you get the proc.
One of the best weapons you can go for is the Overseer’s Guardian. It does double damage thanks to its two-shot property, synergizes with a Rifleman build and is easily available.
Jet is a godsend. Use it if you feel overwhelmed. Better yet, get Chem Resistant to avoid getting addicted. You can build scavenging stations in your settlements to produce fertilizer, then go to your chemistry station to create the drug.
Get a companion. They can distract and tank enemies for you. When they do, you can close in and get those headshots using V.A.T.S. or just shoot them the old-fashioned way.
Use terrain to your advantage. Ghouls, wild dogs, deathclaws and other melee attackers won’t be able to hit you if you’re elevated. They’re smart enough to use line-of-sight against you though, so be ready for it.
Use line-of-sight. They can’t hit you if they can’t see you. If you move out of sight, they’ll usually close in on you. Camp a corner, then spray them with bullets once they come into view. You can also try to go for headshots.
Running away from a fight is usually an option. If you didn’t initiate the fight, it might be prudent to back off then sneak. Wait for [DANGER] to go away then come back and reassess.
Stealth is good but not great. If you want it to be great then invest some points in it. At max level it becomes really, really good. You might want to attach a suppressor to that weapon though.