The showcase should be in south or west side.
Counter should never be in north or north east side, it can be in south, south west, south east, west of north west.
Customer should face west or south side and owner or salesperson should face in east or north side.
Owner/salesperson/accountant's seat should not be under the beam.
Cash counter should be along the south or west wall so it can open in north or east side.
North facing shops are good. Have a good luck for your shop.