First Sunday of the month, after church and after lunch, I sit here and type up a months worth of meals. They are predominantly seasonal (soups, stews, oven-baked in winter, cold or microwave in summer...) and flexible. I also plan for leftover use. Like Sundays crock-pot roast will be Tuesdays tacos or enchiladas, leftover meats get chopped and tossed in soups or chilli.
Grocery lists are done bi-weekly (to coincide with paydays). Menu items use the least perishable items as we close in on shopping day. Like pastas with frozen veggies. Fresh stuff gets used first, or frozen right away.
I split groceries with the family I work with, and I cook M-T-W-F. It is awesome, because I'd cook anyway, and this way less is wasted, and I only spend about half the money. Plus, we all eat better, eat out less, and have lost weight. Well, except lil guy, who is learning to like veggies..... even if I have to hide them.