Here's how I do it. I bought a white board calendar from walmart (like this one) and put magnets on the back so it sticks to our fridge. Every month, I write in what we're having to eat and leave some days open for left overs (L.O. on the calendar). There's a spot at the bottom for notes where I write what ingredients I need to buy from the store.
I know a lot of people plan weekly so they can look at ads and match their meals to the ads, but I find this to be more time consuming than what I want to spend on it. Monthly plans work well for my family. Do what works for yours!
Here's a picture of my November menu (Tuesdays are blank because we are involved in a program that serves us dinner.)
Crockpot BBQ Chicken and Halved Potatoes
Pork Chops and Rice
Beef Stew and Cornbread
Buffalo Chicken Wraps
Chicken Fried Rice
*French Dip Crescent Rolls
*Garlic Parmesan Chicken
I always try to do 1-2 new recipes every month. The ones for this month have a * next to them. If you would like recipes for the ones that don't have a link, let me know and I will be glad to post them!