I have a 3 ring notbook with all my favorite recipes in it, and recipes I want to try. I get a piece of paper out and brainstorm what sounds good for the month, then I pick out some recipes to make up enough meals to get to the end of the month.
I go by themes to, kind of, Monday is kind of what do we need to use up night, Tuesday is ground beef, Wednesday is clean out the fridge, Thursday is pork, Friday is Chicken, Saturday is quick and easy, and Sunday is a nice beef dinner.