At joerhoney.com, many years of experience and much care go into color-separating for screen-printing. That’s why here, it is done manually, without the aid of color-separation applications or plug-ins that always choose the same set of colors from one job to the next. Tight communication is asserted with the screen-printers as well. This is to ensure that the end product looks as close to the originally approved art piece as possible.
Example:
Before:
Here is an art piece supplied by a client, requested to be setup for print on black shirts:

Artwork copyright Tiki Time™ Pools.
After:
This is how the artwork looked after being setup for screen printing:

Breakdown:
These are the colors used in this piece:
black:

aqua:

green:

yellow:

red:

white (for highlights):
