I know most people will know how to do this, but if anyone happens to be interested, then this might help out. And that would be awesome.
1. Scan Sketch and open in Photoshop.
2. Change Sketch layer to "Multiply".
3. Create "New Layer" under Sketch, and paint on this.
You can merge all the layers after this step if you want to go on and create a clean render free of sketch lines. But for these early development sketches, I think leaving it at this stage gives it a much more appealing illustrative style.
Did anyone find this was useful or interesting? How do you paint over your sketches?
I quite enjoyed making this. I know it's insanely basic, but for my first "tutorial" I didn't want to do anything complex.