Where can I learn to model low poly like pigart does ? He is know on this forum as “TheNewGuy” I think.
Mostly focus on reference modeling.
Thanks in advance and sorry if there is already a tutorial that I didn’t see,just guide me to it ! 
You can see in his video that each elements in his work is individual objects. So it is a matter of learning to build low poly objects like rocks, water, land form, mountains, trees, and clouds. Practice building those details. Pigarts basic approach is to create rough form first. Sub divide it. Use Displace modifier to make it bumpy. Than use Decimate modifier to make it low poly again.
And then comes combining those elements to make a picture. It is a compositional problem. Pigart example shows he get his idea and inspiration from illustration. That is the starting point to start arraigning objects to make a picture.