Edit: Adding some more serious things, mainly details for those keen on following it up and using the techniques as good as possible.
First of all, this tutorial is older than the painting tutorial I did, also to be found in my gallery under 'tutorials' or simply here: [link] so some of these techniques may not be up to date in terms of 'how I work'. Colouring is a key element of yoru work, but it grows along with you, it evolves, changes... These basics can help you, but by no means should you follow them like a rulebook. The tutorial is here to help.
Second of all, more about the tutorial itself, is this: Even though I mentioned extra layers of deeper shadows are 'optional', you might want to note that in most occasions it looks a lot nicer to actually go and add them. Deeper, more saturated shadows can really give your drawing more depth. The tutorial mainly talks about how to do it, but choosing your colours is part of the process.
Here's a last tip I can give. Use surrounding colours in your shadows. It's a real lifesaver to me. Is your character wearing dark clothes? The shadows of your skin cast by the clothes, for example under the sleeves, should have a bit of that dark colour in it. Is your background/clothing/hair/whatever light? Add some light reflections to your deepest shadows. Experiment with it and you'll see, it helps your character blend into it's surroundings.
FOR MORE IN DEPTH STEPS ON SHADOWS WITH THE COLOUR PICKER, CHECK MY OTHER TUTORIAL "[link]"
-end of edit-
BAM IN YO' FACE I'm workin on this piece and decided it would be the perfect opportunity to do a tutorial on colouring (mainly skin, but you can apply this to anything really, it's more about how to use pen pressure to your advantage)
So, hope it helps you. I got tired of editing it, so please let me know if I let in any typos or something. Might make one about hair in the near future.
wahhh! helpp mee!! *tear* okay so i get the whole sketch layer final layer, that i get but when im trying to put the base colour down how i can i get it to be the layer beneath the lines?
If there's any questions or things I explained too briefly you can always let me know, heh.