Now I have like 300-400 Forgotten Souls after all this Rifts.I collected Forgotten Souls during normal and Greater Rifts (by salvaging legendaries I dont need).I run 20-40 GRs solo and upgrade legendary gems.I use 'Hope of Caine' (Not 'Law of Kulle', it is used later) to use up Breaths of Deaths I collected. I run normal Rifts until I have 20-40 GR keys.My personal way to gear up is this rotation**:** After that every Ancient item you find/get (even on T1 difficulty) has a chance to be a Primal Ancient. This means that you just need to successfully finish GR 70 solo once. Primal Ancients can drop from any source of Legendary item in the game, including Horadric Caches, Kadala, and Kanai's Cube, but only after having completed at least a level 70 Greater Rift. Let me quote the Diablo 3 Wiki about primal ancient items: Just reroll your weapon with 'Law of Kulle' and you should get an ancient weapon after 10-20 rerolls. Use that mats and Souls in Kanai Cube for ' Law of Kulle'. Use all Breath of Death you found for the ' Hope of Cain' receipe in Kanai Cube (and hope to get ancients). run normal Rifts on T6 or higher (to find ancient drops). You should use all this ways to get ancient items. On T6 the odds are 10%, and they increase higher on T7 - T10. The odds of Ancient items from all monster, chest, object, Cache, etc drops start at 1% on Torment 1, and increase steadily with the Torment level.Ancient occurs on about 10% of legendary items obtained via gambling, crafting, or Kanai's Cube recipes, with no increase by difficulty level.

Let me quote the Diablo 3 Wiki about ancient items:

Diablo 3 how to get primal ancient gear