Give Discount to the next order of the customer on the basis of current order‘s Cart Total Amount, Purchase Product Quantity, Minimum Orders done, etc.
Give additional restriction also, like exclude category, exclude product, exclude sales item.
For making this discount rule select Discount Rules tab.
Now choose Next Buy Bonus.
Now click on Add New Rule.
Now your Rules are active and if anyone buy the number of product or the amount total which you have chosen, they will get discount on their next order.