Grayscale to Colours Tutorial

Hi people. This is a tutorial about how to colour a grayscale piece. Many people have asked me for this, so here it is. There are MANY many -I can't stress that enough- many other tutorials (video tutorials even) about this, by more experienced people also. You might want to check those too. But I spent the first day of this New Year working on this, because I want to help others as others helped me, like *SicilianValkyrie , who gave me some tips.
I really hope it's useful.
Comments more than welcome!