Your best bet for redesigning your shop would be visiting some already existing shops and drawing inspiration from them (don't outright copy, but you get what I mean). Feel free to visit my shop (AshiMagari's Shop) and my friend MaddKat's Shop for ideas about designing ^^
Im not good at designing shops, but have the items really organized in like section (ex: An Easter section would have pastel flooring and rainbow behind the shelves and flowers, Easter deco)
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http://forums2.cubiccastles.com/index.php?p=/discussion/632/full-guide-on-how-to-build-a-good-shop#latest