Simple 2 color sep in Photoshop with a base for screen printing. 

This vid simply covers the basics of a 2 color separation using a base white and a back ink on a budget order. Typically, I would prefer to use at least a mid tone grey as well and in some cases, even 2 or 3 grey's depending on the art and customer, budget and need to impress. The best greyscale photo image are done with multiple shades of grey.