Danyl Bekhoucha's 'Dark Blender' offers an automated workflow to convert hi-res models (like sculpts) to low-poly optimized game assets.
Discover Dark Blender a modified version of Blender that include various scripts and tweaks to make the creation of game assets much faster. It is particularly fast for stylized asset such as Dota. It include a script to generate a low poly, a greyscale, save your textures, put them in layers to make them ready to paint from your high poly in one click at your desired polycount!
You don't need to know anything about Blender or 3D in general because you can focus on sculpting with Dynatopo (you don't have to worry about the faces) then you run the script and you paint on your model.