I think the lettering and your drawings are too different in style. The eye is drawn too quickly to the words when I feel your sketches should be the focus. Try getting rid of the words and putting other drawings in their place. (Also, white works best to me- I think one of the things that works about your shirt is that it could look like someone hand-drew those images on the shirt itself. On that tip, you might want to try redrawing everything with a thick sharpie to get some more line weight variance.)