The first step toward having a healthy poinsettia throughout the holiday season is to choose a healthy one to begin with.
Choose a poinsettia with dark green, healthy-looking leaves that are not damaged or wilted. The actual yellow "flowers" of the poinsettia, called cyathia, should be tight, not fully open. Avoid poinsettias whose colorful red, pink, or white leaves, called bracts, are curled or soft.
Poinsettias do best with 6 hours of natural light per day. Avoid direct sun, hot or cold drafts, and excessive heat. Check the plant daily and water as soon as the surface of the soil feels dry to the touch. Water as much as it takes to have the water come
through the drainage hole in the bottom of the pot, but be sure to remove the extra water so the plant does not sit in it after watering. If the plant has been wrapped in foil for gifting, allow the water to drain from the foil after watering.
It is possible, with some effort, to keep a poinsettia and have it bloom again the following year, but the results usually are not satisfactory. Enjoy the plant through the season and into the winter and plan to buy another for enjoyment next year.