Maybe my strategy will be underwhelming to you but I believe in keeping things simple & doable. Like everyday doable and with kids (for those of you who can relate). I actually use the "Notes" App on my iPhone to keep both a meal plan and a grocery list. My phone is almost always with me, so I like the ability to add items to my grocery list as soon as I think of them (in the kitchen, while feeding the baby, waiting at the doctor's office, in the middle of the night when I can't sleep, etc.). I can't tell you how many times I've done our meal planning in bed as we're going over the upcoming week (coordinating schedules & such) on Sunday nights. It's actually become a weekly habit that keeps our household running more smoothly & healthfully. :)
If you're like me, if an item doesn't make it on my list, I'm likely not going to remember to get it while I'm at the store. Which turns into more trips to the grocery store, which also means I'll spend much more money. I seriously love grocery shopping (especially at small grocery stores like Sprouts, I could literally spend all day there), but that's a story for another day! :) So yes, having a current and complete list is also a money-saving strategy for grocery shopping lovers like me!
When there aren't any leftovers for lunch, I'll whip something easy up if I'm motivated but otherwise I'll make a protein green smoothie or snack on homemade jerky, some veggie (often carrots because I can get an organic 5 lb bag at Costco), maybe a 1/4 cup of mixed nuts, and a piece of fruit.
So based on my simple meal plan, I create a grocery list of the items I still need for those meals. Here's an example of a fairly typical weekly grocery list for us. To make it a little more organized, I like to break up my list between the stores I will get the items. That's mostly based on the quantity our little family can get through without the produce going bad or who has the best organic prices (where our budget allows).
I like to pick nutrient-dense foods that are extremely versatile. For example, I can use spinach in a green smoothie, I love throwing a handful into an omelette, it makes great salads, and can even be use in a stir fry. I also like going for simplified food prep, like buying a big bag of broccoli florets from Costco because they are already washed and cut up!
What's on your meal plan for the week? What do you do for easy meal planning and prep that works well?