Make sure the platen/table height is adjusted so that the shirt is 1-2mm from the print head. Load the shirt, then use the "Auto" option on the machine's Control Panel to automatically adjust the height.
Be sure to press the shirt fibers down first (don’t use any parchment paper). If you still see fibers clearly standing use a fine mist of water and then press the shirt.
Inspect the nozzle plate with a mirror and flashlight and be sure to clean the edges of it very carefully.