There is really only 1 straightforward way.
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Helltides - preferably blood maiden until temper unlocks, chuck on a few % chance to do xyz damage on weapons, the burst tempers.
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Once you unlock capstone do it immediately it should be easy using basic tempers and you should have plenty of gear from helltide.
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WT3 start infernal hordes, level until you can do the next capstone, again best gear you have available, rudimentary paragons if you wait until 50 and tempers.
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T2 Infernal Hordes the rest of the way until you can comfortably T3 horde (hordes are the best exp in the game without any competition).
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Always have potions up, once leveled enough add incense. Don’t forget to swap from t1 to t2 potions when you hit the right level.
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Caveats are mythics, if you have mythics, Masterwork them, unsocket gems, and then wear them from level 35. You will be laughing all the way to 100 with any mythic.