This is how I do it… I get my character to 70. Then I do a few GR’s, so I can get a LoD. Then I just start slapping on legendaries, trying to gear my built to what I have. I always say that the wizard is the best way to take this route. Soon you start climbing in GR’s, getting more legendaries so you can start equiping good legendaries. All the while, you are building your LoD… Usually that gets me to GR 70 in a few hours, taking it slow and easy… Good luck and Good hunting!!!
Sounds like you have Inarius. In that case I would go for the Bloodnova build: get the Iron Rose off-hand, and just syphon blood like crazy. Throw an Aquila in the cube, the Deathnova 2hand scythe, and an RoRG, so you can add golem breeches. That should give you enough toughness and damage to get you to GR70 so you can start farming for a really good built (I like solo-Skel Mages, Masq & a better version of Inarius Blood, but there are way better and harder to play-gear Necros!)