I love how luminous your paintings look!
Very nice soft light and good composition.
Your sense of color is lagging behind, though.
Especially when you go from b&w to color and don't really know what you're doing you often end up with very bland and monochrome colors.
If you're using overlay to color set the value to 50. Saturation is important, too!
When coloring skin try to throw in some pinks and reds where the skin is not as thick to make it more lifelike.
If you have trouble finding a general color mood for you image try using Color balance adjustment layers.
This is such a cool sketchbook, looked through it many a time but realised I havent put in a comment yet. I Really like the portrait in post #420, it has a really intent feeling to it. Awesome stuff man, keep up the good work, cant wait for the next update!
DeviantART // My Sketchbook
If you have the time please show me some love and +watch or come by and check out my progress and crit me!