Years ago, my dad gave me a tip. (Background: I kill plants! I so do not have a green thumb.) For a poinsettia, add ONE ice cube each day to the plant and no other water. It works like a charm!
Also, DON'T place plants near cold drafts or excessive heat. Avoid placing plants near appliances, fireplaces or ventilating ducts. DO place your plant in indirect sunlight for at least six hours per day. If direct sun can't be avoided, diffuse the light with a shade or sheer curtain.