COLOR

So, this is how color works inside computer.

Red is next to Orange, and when you move Red, a lot of times the Orange 'needs' to move.
Red is like best friends with Orange.
When you gank up the Reds, for example, to the intensity you desire, sometimes you're putting Red in a situation where it gets pretty far away from Orange.
Thus, color splits and suddenly your smooth gradation from Red to Orange gets shagged like Grand Canyon.

Nowadays computer does it all for you, but, the key is to get these guys to line up so they don't bounce out. Purple and Magenta is an exception in this image, because I barely have purple and magentas in my photo (this time).

Make sure they look nice. Like "oh that looks cool" or "pretty".
Usually they need to be aligned smoothly in order to maintain the quality of gradation.