OP - HC requires a very different mindset from SC. You do NOT push harder before you have the gear, with the right stat rolls. Doing so puts you at much higher risk of dying.
Know your mobs - certain mobs are instaquit, as are certain RGs.
Patience is a big thing too, don’t rush your progress through a rift or GR.
Be wary of bad maps such as banished realms or barracks, both of which are spawning an awful lot this season.
The below advice is really for s6 impale…
I tend to push with diamonds in the chest piece for extra AR, and amethyst in the pants for extra vit. I run s6 impale, and I run with vit on gloves (rather than IAS or AD), and vit on the off hand quiver too (sacrificing either impale dmg or chc as you can’t have both this way!). I tend to run with aughild’s set too, which adds nice DPS and toughness boosts.
I tend not to push high GRs until I’m p800 and have at least 5 ancient pieces.
Make sure you get the belt with lpk as a secondary (dex/vit/%life/AR), chest with dex/vit/AR and -dmg from melee/ranged (take your pick) and lpk. If you can get lpk on your ammy and bracers even better. lpk on your karleis is a very good idea too.
2nd edit: with lpk, it’s important to run lightning dmg/impale ricochet rune imho - whilst cold can potentially hit more targets, it’s not a given. lightning will hit 9 targets (if there are 9 in the area of attack of course!). AFAIK, the lpk works on every hit, so if you have 9 daggers hitting a target, that’s 9 lots of lpk…it really helps with recovery and if you take a hit, you almost instantly get life back.
Once I get to around p800 and have 5 or more ancients, I start working on augments, only going up to lvl 100 (means pushing up to a GR99) - which should be doable as long as you’re careful, and slow and very aware of the mobs/elites/RG that spawn.
If you see dervishes or sand dwellers, do NOT engage. Run like hell. They WILL instashot you. I nearly died (procced awareness) on a low level GR95 a few nights ago cos I went up against a frozen/waller/horde elite mob and was kiting it and up from nowhere pops a sand dweller and bang…
I would not run UE MS on HC, it’s way too fragile, even with CCR imho. impale s6 is a much better option for HC pushing.
Also, have separate characters for your HC builds, don’t use the armory. I have a UE MS character for farming gold/mats/DBs/keys and my impale for pushing GRs. I use the UE for leveling gems to around GR64, then switch to impale for getting them up to lvl 100.
Know your limits, know the mobs, take your time.
One final note - if you proc awareness, do not carry on. TP back to town (if safe) or quit the game. Better to live to fight another day than be a hero and die. It goes without saying to ALWAYS run awareness. Trade some DPS for it. A dead DH doesn’t do any DPS.
edit: I run with vit on both rings too…at least until I get to much higher paragons with full augments.