You know that slow mellow music that they always play in stores? It's designed to get your to move slowly through the store, ideally filling your cart as you go. Studies show that classical music makes you buy more expensive items, too. So bring your own music, and play something loud and fast paced to keep you moving through the aisles quickly!
Most grocery stores place the expensive brand name items right at eye level, where you're most likely to see them and buy them. Sales, brand names, and larger packages (with lower per-unit prices) are often stored lower on the shelves.