Can anybody who uses Paint Tool Sai with their tablet give me some advice on coloring? I've seen various tutorials on different ways to do it but they are a bit complicated for a newbie like me :P

I'm decent at getting some lineart, but when I try coloring, especially realistically, I suck. Maybe I just don't know what tools to use when? I don't know.
I tend to use the pen tool and do some nice cell shading then to polish it all off I finish it in photoshop or any program really that contains "Gaussian Blur" and duplicate the layer, use Gaussian Blur and make the blurred layers format "Soft Light" or "Hard Light" whichever looks best and this is usually what happens left is before and right is after, practicing different styles of shading usually goes well but it's all down to what colors you pick in the end, try to use Saturation to your advantage and I hope to see some good results.