Plastisol and Waterbase inks work well depending on design and color of garment. Discharge can work however discharge ink will generally only bleach the cotton and the unbleached poly will affect print look.
On colored garments (usually other than white) it is recommended to lay down a poly blocker to keep the dye in the polyester fabric from migrating into the ink and changing the print color. Dye migration can happen hours or even days after the garment is printed.
The blocker can be either a white or gray blocker (gray blockers tend to provide a better barrier) and generally are cured at a lower temperature (consult your ink supplier). Good idea to print a sample and let it sit for a couple or even a few days to be sure your print color is still correct.
Always use tight screens. Mesh count will depend on design and can vary job to job. Curing temperature around 320* for plastisol and around 300* for water base. Again these depend on individual dryers as well as the amount of inks used (consult your ink supplier).
Works best on 100% cotton (and 100% cotton face) fabrics. DTG also works on cotton/poly blends requiring a pretreatment to help the print quality and adhesion on the poly portion. The higher the poly content the more the need.
Washing a printed sample garment is recommended to be sure you have proper curing and ink adhesion.