Follow the season journey and get your free IK set.
http://d3resource.com/journey/index.php
You already did the hardest part, getting to level 70. IK is our utility set so you can adapt skills (you can even whirlwind with it) to whatever legs you find as you farm Wastes gear.
I also suggest reading this stickied thread:
Section 2 has advice on skill choices for when you don’t have a set yet.