Down at UNIQLO they have some Star Wars T-shirts which feature some nice artwork. They foreground previously marginal images from the films and use cheerful colour schemes. They images used are simplified vectors and probably work well for screen printing.
I did a quick and dirty example to show you what I mean.
I used the Trace Bitmap function to vectorize some images from movie stills and arranged them in layers. The star field was created as below. Play with the values to get exactly what you’re looking for.
Draw a circle around 10px x 10px
Edit menu > Clone > Create tiled clones
20 x 20
Use saved size and position
Shift X 200 200 1000
Shift Y 200 200 1000
Scale X 0 0 100
Scale Y 0 0 100
Rotation 0 0 50
Blur 0 0 50
Opacity 0 0 50