Improper watering is one of the main reasons for the decline of poinsettias. Be very careful not to over-water! Water your poinsettia only when the soil becomes dry to the touch. Keep the soil slightly moist, but do not let the plant sit in water. The shiny paper surrounding your poinsettia is pretty, but it prevents the pots from draining properly. This wrapping should be removed whenever the plant is watered and can be placed back around the pot after the pot has thoroughly drained. Pythium root rot, caused by over-watering and/or poor drainage, is one of the most common causes of death of poinsettias.
Place your poinsettia in indirect light. They need six hours of light daily. But be sure to “keep it cozy” – poinsettias do best when the thermostat is between 65 and 75 degrees. Keep your plant away from cold windows, warm or cold drafts from furnaces or air conditioners, and open doors and windows. Do not fertilize poinsettias while in bloom. If you manage to keep your potted poinsettia alive until next fall, you can trick it into bloom. They need at least 12 hours of complete darkness each night for 6 to 10 weeks to trigger bloom. Every night place a lightproof bag or box over the plant or put it in a dark closet. This is key to getting them to bloom in time for Christmas 2016!
Side note: Though they have a bad rap, poinsettia plants are only mildly toxic to cats and dogs.