I would say helpful employee's are a must. If you have a sample up in the store, have the pattern for it...there is nothing more frusterating then seeing a pattern that you like and being told that they dont have it anymore.
I like the technique of the month ideas too. Just something small so you can try something before you commit to a larger project.
Block of the months are good too, I did one that you had to show the last block before you could get the next block and it made me actually keep up with it.
Good lighting! Can't say enough for the stores that are over packed and dark that makes it hard to look a the fabric and truly see it.