Giant Robot T shirt colors

I've been working a bit on trying to make a new t-shirt. One thing that's hard about shirts are the color combinations. How do you pick? The colors you get on your computer don't exactly translate to inks on shirts. Does red really show as a nice red on black cotton? Does red and yellow look good together or is it too USC? Will people buy that forest green t-shirt? In the end, I tend to make shirts, either black, dark grey, white, navy blue, and brown. What else is there? White? bright Green? Maroon? With shirts, I've learned that you have to play the percentages and hope for the best. We'll see what happens from computer to final print job. (I'm not including a photo for this thought, since what looks good right now, might look like crap an hour from now).