I feel like you're on the right track, but you could stand to make some improvements.
This picture feels like it doesn't quite jive with your art style. I can tell that you have a very rounded style, in contrast to the more angular style used in mid to late Z and GT. There's something about the face that just bothers me and I don't think you have the musculature right. A character's neck shouldn't be that thick and their upper body shouldn't be that much larger than their lower body unless they're an over-muscled body builder or the Hulk. (or you're stylized toward that kind of thing, which you really don't seem to be)
In general, I'd say to loosen up with what you're drawing. It's pretty good, though.
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