You probably spend as much time at your shop as you do at home, at least during the first few years, so include a few amenities to make life more comfortable.
A small kitchen area with a refrigerator, microwave and sink will be appreciated by your staff as well. Make sure there is a place to relax, with comfortable seating and good reading light. You don't need to be stuck in a corner surrounded by stock!
During the day, the shop belongs to the public, but in the early morning or late evening, it's all yours. Enjoy the calm and solitude, and the opportunity to get some work done without the distractions of customers and staff.
There's no reason not to have a pair of ugg boots or thongs tucked under your desk and a collection of favourite music to listen to when you're working late or early...