If your skill is in guns, get the riot shotgun (the one with rapid fire) it blows them to bits.
Or the Anti-Material rifle. Or a bigger gun like the Minigun or its unique variant the avenger or something.
If your skill is in Energy weapons, use a plasma caster, Laser RCW, Gauss Rifle, Gatling laser (though I've yet to see a Gatling Laser in New Vegas I only assume they're in this one too).
If you're an explosives expert, you have a really easy time. Build bottlecap mines, use frag mines, or any other explosive you can place and backpedal while placing them. At the very least, their legs will be crippled. You'll need quite a few, so if you're an explosive user, collect Lunchboxes, cherry bombs, and obviously bottlecaps anytime you see them.
If you have unarmed or melee skill, you need to focus on Endurance, strong armour and medicine.
But level up first, you can't take Deathclaws on at level 2.
You can outfight anything that shoots at you like a regular shooter, but you can't do it for fast creatures that use melee.
My character is energy weapons/explosives focused, with low endurance. So if you're in a similar situation to me, use a follower like Lily or Veronica to tank damage for you.
Good luck.
I play Very Hard,Hardcore and modless, even with my endurance so crap I can still fight big baddies like Deathclaws, you just have to be really careful.