Always try to kill alphas and mothers first. Once you initiate combat, if you are not prepared, these things will be your worst nightmare. They are stronger, faster and more of a pain in the rear. Another thing to keep in mind would be to keep moving. Never stand still, as the deathclaws are much faster than you are, and if you stop to shoot, you are dead. So a tactic that I use effectively is to get either a high powered rifle such as the AMR, the Sniper Rifle, the Hunting Rifle (Or any weapon in 45-70 Govt.) and start out far away sniping. Pretty common suggestion. However, when they get close let them lunge, and then jump out of the way. If you time the dodge right, you should have a chance to fire before the try to swing again. If this kills them, good. Save and then move on to the next one. If not, repeat until they die, or switch to an automatic weapon (Try and avoid cumbersome heavy weapons) and aim center mass. This should help you out. Have fun in New Vegas! And good hunting friend!