1st, is this image just for reference or do you have a larger higher res file to provide? If not, your going to have a problem with image quality (if this is the actual art file). It's 3" wide x 2" tall (low rez quality image). I can bring it in larger in Photoshop, but as you know, ...drap in, crap out.
I have plenty of customers that say, (this is all they have) and are ok with whatever results we get. So, I do the best I can. It seems to be about 40% of the sep work I get, but I do charge a little extra for clean up.
Shirt colors for highlights
1 Medium gray
2 Army Green
3 Black (1 screen) since it has no black type.
$45.00 if good art is provided. A little extra if not.