I'm working on the Great Khan quest for the NCR and I'm trying to convince the people to speak out against Ceaser but I can't get to the encampment by the Quarry. Does anybody know how I can get into this place cause it's pretty frustrating

You can either clear out the deathclaws in the quarry, or you can approach from the southwest of the marker. There is a ridge that you can follow, just above a small Khan encampment (just a campfire with some Khan scarecrows). If you follow the ridge northeast, it'll put you just to the north of where the marker is. You'll still need to deal with a few deathclaws. You can either sneak by them or kill them. It's still easier than fighting the whole quarry.

I had the same problem as you. They really hid that place well.

EDIT: Think I might've misinterpreted the question.

Ah man I am really not looking forward to fighting these Cazadors and Deathclaws. Guess I'll have to leave Veronica behind on this one

What's your prefered attack skill and what number's it at?

I cleared out lots and lots of Cazadors today (they're thick up in the mountains west/northwest of Vegas). At 50 XP each, I got quite a few levels while traipsing around up there. I had Veronica and ED-E with me, but they only fought at close-range.

Hunting Rifle, Guns 50, regular .308 ammo - can do quite a number on them if you get a sneak attack. Reload time is quick enough too. But VATS, takes nearly a whole bar to get off a single shot. Big advantage of the HR is that you can engage from maximum range, and whittle it down at least halfway before it starts homing in on you. The Varmint Rifle or Ratslayer just doesn't have the punch. The Trail Carbine might also work.

10mm SMG - This actually works fairly well because you can dump a full clip downrange, which makes up for the lower theoretical DPS over the Hunting Rifle.

Hunting Shotgun - with the Shotgun Surgeon perk and regular ammo - this is my preferred weapon for close-medium range. 8-shots in the clip, but it's a manual reload cycle so make every shot count to the best of your ability. I can squeeze off two shots in VATS when they are within spitting distance to finish any off. The choke to reduce spread is highly recommended along with the long tube so you have 8 shots instead of 5.

Bring anti-venom, simpaks, super-stimpaks and doctor's kits (if you're on hardcoe mode). Foods that heal 40-60 points of damage are also recommended.

Deathclaws... sneak attack with the HR takes a chunk, but it gets really dicey after that. I may go back and try them now that I have the shotgun surgeon perk and a hunting shotgun.