I think one of the most important things to do is critically listen to a track which you like / admire the mix of.
Experiment using all the techniques used above to try and mimic the sounds that the artist in question is achieving.
If those artists are Skrillex / Deadmau5 / Madeon etc. it won't be easy but I promise you'll learn a lot. I would save a copy of your original song file and just mess with it. You probably won't get exactly what you want first time but you'll learn a lot!