Machine wash cold. If you have a top-load washer with a centre agitator bar, turn the garment inside out before washing.
Tumble dry low or hang dry. Iron inside out and avoid ironing directly over the print.
Skip fabric softener when possible. If your graphic arrives with a wrinkle from shipping, turn the garment inside out and use quick passes with an iron on low heat. No iron? Put the garment in the dryer on high for 5 minutes, remove it right away, lay it flat, and place a heavy book over the graphic while it cools.