(colour help)
right mate i know exactly what the problem is. You need to paint in your background in first. this is very important so that you can then get the environmental colour. the environment always effects the skin tones nodnod. right for the base of the skin choose a mid tone pink. paint this down on the character. Now you need to get the rest of the skin tones. Skin is not make up of one type of colour with varying tones. that will make you painting look monochromic and false. To get your tones mix your mid tone skin with some of you bg colours. this will get some nice variations, do about 3 or 4 colours. Make some lighter colours and darker ones. Now paint these onto your character in the right places where the shadows and light tones lay. Now we need a pure highlight. pick the lightest tone from your bg and apply it to the character. (remember to blend the colours all together lightly) for realistic lighting use a really light sky blue colour which is nicely saturated. For shadows make a really dark tone mixing a skin tone to the bg colour. (a little tip- if the lightight cold try using a warm shadow to contrast and vise versa).
Lastly create a new layer set it to colour mode with a low opacity. run reds and oranges over the cheeks and nose and places where more blood will be. (look at refs) run lightly some blues and greens over some places like the eyes. Also add purples to the face to. these colours are ment to be very light and subtle.
these are things I use to paint my character. plz do look at refs to help. Visit my website mitchellnelson.deviantart.com to see some examples of what I do to create effective colour harmony.
(Brushes)
For the brushes I use a hard round brush with other dynamics set to pen pressure. I do this to get base colours down. i just block them in roughly. Next I create a custom smudge tool brush using a chalk brush. I change the angle jitter so its a little jittery (NOT ALOT!!) this just smudges the colours together.
never use a soft brush untill the final blend. cause it can make the painting look air brushed and almost plastic. I would use the air brush at the very very end and with a very low opacity on a new layer just to lightly blend the colours in. (you will want to keep some little brush marks to make the painting more visually pleasant.)
I hope that helps. just visit My Deviantart to see what i mean by all that. look at my sephiroth painting or the wandering minstrel painting those are 2 good examples.
visit my website at mitchellnelson.deviantart.com