In a shop, supermarket or gas station for example you will see in a strategic place the finest flowers. Often you will see great mixed blooming flowers wit a lot of green.
Often in these bouquets you find also, quite short cut lilies and especially Oriental species. Too bad is that this mix never performs that beautiful lily. Most flowers around the lilies are allready in full bloom before the lilium blooms and the lilies have too little space to show full advantage.
So do not buy a mixed bouquet, which will also be more expensice, but look out for those beautiful long lily stems. Note also the buds, they must show slightly the color of the final flower. The shop cuts the lilies often very raw (green buds) and that has as a result that the real green flower buds not open because they simply lack grownth.
So ask for reasonably ripe lilies, prepare a beautiful high vase and place between 6 and 10 stems into the vase. This is of course dependent on the size of the lily against the vase.