That's good advice from Piston. It is a solid style and nothing wrong with experimenting with it until you master it. But don't be afraid to try new things just because it doesn't look good. That's the only way to expand because you sure as hell aren't going to learn anything if you're doing...
Some additional concepts:
• more playful version of the original concept
• a book concept
• and an interpretation of what a childrens hand-shake would be like. hand-prints overlapping.
• also experimented with more color combos but the blue/yellow/green is the strongest imo
pre' cool. Simple but nice. The mosaic is doesn't go with the style of the rest of the piece. Just get rid of it, doesn't add anything to design. I like the colors. I feel like it could use a cream color as an accent, though.
Good werk.