The white highlights on the dragon kind of distract from the main design to me, but i think the overall concept and mailman is very very adorable. You might consider a bit of a sky background or brightening up the shirt a tad, also a bigger center placement. Nice work!
interesting concept, but the colors are a bit jarring. perhaps make the Tee darker (like a forest green) and the dragon is a lighter green (like an olive or maybe a lime green)
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