Here is a simple tip that often is the fastest and more efficient way in retail to improve your turnover. It is simple try and sell more to your top customers by trying to sell them more of what they are already buying off you. If they are buying blue pens, try offering them a bigger box of blue pens. If that does not work try a range of different coloured pens. Try and make it as close to what they are buying off you now.
If you are not sure who your top customers are take a look at your VIP system in your POS Software, it should be able to tell you.