Now a days, I prefer dyed roving. Depending on how it's dyed and howyou draft it can be unexpected results. Don't be scared. It always seems to make great singles. Then you can ply it on itself like navajo plying to keep the colors together or ply it on a white or single color for a great effect.
It's be good idea to get either twisted sisters sock workbook or spinning in color. Once you see that you'll dye to spin color