Not sure what gear you have access too at the moment, but you do have the 2-piece Pest at least. The Black Death is a good weapon, but to get the most out of it you'll need to fire off Poison skills so you can get 4 stacks, I wasn't able to do that consistently so I went with Reilana's Shadowhook which will give you a dmg buff based on your max essence pool, at 330 essence you'll get a flat 165% dmg increase. To make the corpse lances fire off automagically you'll want to apply the Aura rune to Devour. You don't need to equip the Corpse Lance skill to make it work, but if you do, whichever rune you apply to it will be used by the auto-firing lances, the Brittle Touch rune is a good choice.
You have lots of options for Jewelry, the Endless Walk set and Unity (if you have 2) are a good combo for survivability, but you could also go for a Goldwrap / Avarice Band / Hoarder gem.
Ideally you'll want to work towards getting the Inarius Set to run Bone Storm, it is so good:
Necromancer Bone Storm Build With Inarius Set
That is what I am using now and can easily clear T13 Rifts and lvl61 GR's (haven't tried going higher yet). I have all the gear recommended by that guide, but I don't like Decrepify, so I'll wait til they fix Dayntee's Belt to work with Frailty. What I use right now is:
https://us.battle.net/d3/en/profile/Zindan-1920/hero/90467305
Gear isn't optimal, and my character is really squishy if I stay still for too long I'll get killed easily, so I just run around and let Bone Armor / Mirinae / Pain Enhancer and all the dmg stacking kill stuff, and use Land of the Dead for multiple packs of elites/champs or the RG.