Plastisol, Waterbase, and Discharge inks work well depending on design and color of garment. Discharge inks are used without a flash underlay as they bleach the color out of the cotton while adding the ink print color.
Flash underlays for plastisol and water base inks are generally used to make print colors opaque on dark colored garments. Always check on ink flash cure temperature recommendations with your ink supplier.
The underlay color is normally white which is dried under a flash cure unit while the garment is still on the pallet so the additional colors will register on the dry white surface keeping the ink colors bright and opaque.
Always use tight screens. Mesh count will depend on design and can vary job to job, color to color. Curing temperature around 320+ for plastisol and discharge, around 300 for water base. Again these depend on individual dryers as well as the amount of inks used. Consult ink supplier.
Also works on our blends (see cotton/polyester blend DTG printing suggestions) Washing a printed sample garment is recommended to be sure you have proper curing and ink adhesion.