This will come in many parts because I have a lot to say and I don't want one really long post because that will get boring.
The first thing to do is make a list (in an accessible area, or on the computer) of your family favorite meals. Beside each meal, list the ingredients required to make that meal. Definitely do this for dinner, but if you are a SAHM, do it for every meal and snack. Don't worry about doing it all in one day, but add to a bit at the time and always leave room for new creations/recipes.