When selecting poinsettias, choose plants with dark green leaves and well-developed bracts (commonly called flowers). Try to get plants whose small yellow flowers haven't opened up yet. These plants are very sensitive to cold temperatures and need protection when they are transported on chilly days.
Poinsettias prefer at least six hours of indirect sunlight daily. Temperatures of 70 degrees during the daytime and no lower than 60 degrees at night are recommended.
Water plants thoroughly whenever the soil feels dry to the touch. Plants that are in decorative containers or foil should not sit in water.
Contrary to popular opinion, poinsettias are not poisonous. But, pets or people should not eat them as they cause stomach problems.
Reference: Colorado State University Cooperative Extension's Planttalk #1325.