Glasses - Re-Coloring One Lens

Hello! I'm relatively new to CC, though I've dabbled in the past. My goal was simply to create a pair of glasses, where one lens is dark and one lens is light. I really honestly, foolishly, thought it would be fairly simple, but it's clearly not. I've managed to isolate the lenses in mesh form, but when I try to create a texture, everything turns awful and flesh colored and I still can't figure out how to color one lens and not the other. I can't seem to find a solution online, but there is so much information that it's hard to find what I'm looking for. Has anyone done something like this before or does anyone have any tips? 

Thanks in advance!