Why would you do that? For two main reasons: to save time and to improve your health. You probably know what is good for your health, but chances are that it is not good for your taste! Try to make small changes in your diet, and gradually eat healthier. Small steps lead to a better weight trend as you can see on the Change-O-Meter.
Take a look at these websites, they have very interesting ideas.
A Beginners Guide to Meal Planning
15 Tips for Better Weekly Meal Planning
How to Plan Your Weekly Meals, Stress Free