there are a few issues with his six-pack/chest. unless he's wearing the world's tightest tanktop, his muscles wouldn't look that defined through it. also, the middle of his six pack doesn't meet up with his belt, making it look like one of the two is cock-eyed.
His head also needs to be bigger, he looks a bit comically muscley atm.
Other than that, you've picked some nice colours and your hands are lovely!