due to popular demand and for my trainee
i use 7 colors here, but this always of course depends not only on your style (i.e. dithering or not dithering), but also on the size of the base you're going to use. if the base is small you should use less colors, and mostly more contrast in the palette.
you may imitate my technique, but please don't simply copy every single dot or line.
ps: that base is mine. you can find it on my site [link]