Furniture, homeware, kitchen and garden. Coupons in this category almost always carry an order minimum, which is a better fit here than elsewhere because basket sizes are naturally large.
Delivery is the number that decides whether an offer is worth taking. Furniture delivery is priced by item and by room-of-choice service, and a free-delivery offer on a sofa is frequently worth more than a percentage code on the same order.
Seasonal timing is clear-cut: outdoor furniture and garden stock is deepest in late summer, and indoor furniture peaks in January. Buying in the opposite season is the single easiest saving in this category.