Once you've unwrapped and washed the stay-fresh gel from your stems, it's important to cut a half inch off the bottom of the stems at an angle. This will help them get a good drink of water.
Remember to use fresh water and a clean vase, and don't forget to add the satchet of flower food. The stems can be trimmed another half inch every few days at the same time you replenish the vase with fresh water.
Lilies prefer a relatively cool temperature, so avoid placing them in the path of direct sunlight or near areas where they will be subjected to heat or drafts.