Everyone ends up with his own routine. Here are the steps that I follow.
1 Prepare your menu ahead of time
You might be lucky and get everything you need “last moment”, but you are taking a risk of not having enough (having too much) food, or forgetting something.
I usually start menu preparation 3-5 days before the trip. You might need more time if you will be camping for weeks, and less if you are leaving for a week-end. Extra-time is needed if you are dehydrating vegetables.
This menu might not be the “final” version, because grocery shopping inspires and brings new ideas, but you should plan how many meals you are having, and what type of food you would like. Keep the “weight” factor in mind, depending on whether you’ll be hiking, canoeing, or car camping, as well as the availability of grocery stores in the camping area.
2 Purchase all the necessary ingredients
3 Review your menu and separate the ingredients by meals
4 Repackage everything that needs to be repackaged to diminish the amount of waste
If trash-cans are not available in the area where you are camping, you would have to bring all the garbage back with you. Removing carton packaging and putting ingredients in the Ziploc bags saves the weight of your garbage (Ziploc bags could further be used in camping to store the leftovers). It also makes the final “food bag” less bulky.
5 Place meals into Ziploc bags (meal bags). Then you can place all the meals for a day (2 days) in the bigger bags (day bags)
This organizes your “food bag” - you won’t have to hunt porridge packages that fell all the way to the bottom.
It also makes packing you backpack easier – “day bags” are wonderful for feeling out the empty corners of the pack.
Just to clear things up: when kayaking, I end up with 1 or 2 waterproof “food bags”. When backpacking, these are not necessary, since “day bags” are easier to pack.
Update: another common trick is to color-code the meal bags: i.e. all the breakfast bags have a red mark and go into one big red "Breakfast" bag, the lunches are blue and go into blue "Lunch" bag etc. etc.)
6 The multipurpose ingredients could be either further separated into portions, or placed together in one bag (Miscellaneous bag)
7 Take your time to mark each “Ziploc” (name of the meal if it’s not obvious)
8 Write down the recipes/notes on the meal-bags and menu on the day-bags
9 Always bring an extra meal or two
10 Don’t forget to bring a big weather-resistant bag in which you’ll store the food overnight. The bag should be easy to hang on the tree, away from raccoons/mice/bears.
This step is not necessary for car camping and kayaking – you can store food in the car or hatches of the kayak.
Update: Storing food in the kayak hatches might not be a good idea after all. There have been incidents of hungry bears ripping through the fiberglass kayaks. If you want to play it save - hang the food on the tree.