Most cartoons textures are hand drawn to be cartoon textures. I think if you want to paint you own use bold colours and a darker variant of the colour for shading.
Cell shading can be cool too but i guess its not too usefull if you need actually textures.
I would recommend the total textures CD's 14 and 15 from
3D Total - The cg artists home page if you want to work from those. They are very good value.