Don’t over think light and backgrounds when taking portraits at home.
Experiment with both natural and artificial light by using whatever light elements you have around the house. Diffuse the light with white cloth or cardboard. Try bouncing light off the walls or ceiling to soften shadows.
A wonderful way to observe light and shadow is to take an egg, place it on a plain sheet of white paper and photograph it on the kitchen table. Move your light source up and down and change the distance to your subject.
By moving a lamp around the table and at different levels and distances you can watch shadows build and fall.
Friends, family and pets make wonderful subjects and since you already know them it takes some the awkward silence away from your first meeting and your rapport is built.
Think high and think low. Most images are taken at eye-level and its fun to experiment with angles. Remember that you can empower a subject by shooting from a lower angle and make them appear vulnerable by adding space and shoot down on them.
Be patient and have fun, remember that for every rule in photography there is a good reason to break it!