That is a tricky (though awesome) costume. Personally, I would probably scour eBay and such for a pre-made jumpsuit that fit the bill and then sew all the muscle lines on. The darker ones, like on his thighs, I would probably use bias tape (or maybe black elastic, depending on the elasticity of the base), and then the ones that define his abs could be done with just thread. If you really want to make your own jumpsuit to start, I recommend creating an ask thread in the Fabrics subforum. Those guys really know what they're talking about when it comes to starting from scratch.
Scarlet Witch (with Quicksilver), Dagger (with Cloak, 2013 Ultimate editions), Stahma Tarr, Pyrrha Nikos (with Sun Wukong)
Chosen, In Planning:
Red (with Subject Unknown), Tempus
Ravager, Sakhmet (with Inanna)