OK, let me try to narrow it done. I do not use sneak or a melee character and mostly I use guns. Does that help?
Hand Loader. You'll be able to easily craft bullets that do more damage in all the more damaging guns you can use.
Sniper: Head shots do double damage in a majority of the creatures you shoot at.
If you love doing critical hits, wear Boone's hat, get the Finesse perk, get the Better Criticals perk, and use a Sniper Rifle (or the unique one as well). You will almost ALWAYS land a critical shot, more than doubling your damage. Combine a critical shot (enhanced with the Better Criticals perk) with a headshot and you're essentially quadrupling your damage for each shot - provided you're using a Sniper Rifle or another weapon that has a high chance of making a critical hit. Combine all that with a hand-loaded .308 ammo you can craft which increases your damage by +50%, and you stand the potential of being able to 1-shot almost everything in the game - that's not an exageration.
Everything else beyond that deadly combo is gravy.