In terms of general, everyday planning (as opposed to planning for T-Giving or Christmas, say), I try to look at the diary for the week ahead and take account of what days DH will be late, any days I may not be around (DH can and does cook well, but after work he needs simple dinners for he and DD), and any days that all 3 of us may get to eat together (often, DH and I may eat together once DD is in bed, as he is usually in later in the evening - sometimes it may be that DD and I eat together and DH needs something seperate).
I check the freezer and fridge for things that need to be used, and a general storecupboard glance. Bearing in mind if I am trying to run down stocks ready to do a big "stocking up" grocery shop shortly, or need space for fruit/veg gluts, or have a busy few weeks ahead where I need every easy dinner I can in the freezer.
I tend to plan a family roast dinner on Sundays, a "date night" dinner for 2 on Saturdays, a "cook the day before and reheat" dinner for Mondays (helps start the week), and usually have another Monday dinner from the freezer on Wed/Thurs (I always do a double batch of something on Sundays, when I am relaxing by cooking anyway). Fri I try to plan as an easy peasy meal, or it will end up as a takeaway night.
We are not far from grocery stores, but it is hassle to go mid-week. So I also aim to only need to go once a week. I do up a rough menuplan for the week, and write my grocery list based on that. (By having it that way, I can change things if I spot good deals or "whoopsied" items).
The other part of my shopping list, apart from perishables that aer needed for the week or specific items for dishes that I am out of, is the list from the front of the fridge. On this, anyone who finishes something has to write it up - so if DH finishes the butter, I know to get more, or I might finish the mayonnaise, which DH then knows if HE does the shopping. We try to write things up BEFORE things get finished, but that doesn't always work. And this also covers cleaning and bathroom supplies which we get at the supermarket, or things like batteries or other things that we need to get from other stores. It's useful.