Yep, Sharpies. Little permanent markers--not too thick, not too thin--that can write on almost anything! In my storage, I use my sharpies mostly for recording dates on items. Of course you can use a pencil and paper and write it all down in a notebook, it just wouldn't be as easy. When you purchase something you are planning to store or planning to use, or you bottle, dry, or freeze something, sharpie the date on it--just get your sharpie out when you bring the groceries home and mark the stuff as you put it away. Then mark it again when you get it out to use it if applicable. Dating your storage stuff serves a few different purposes.
First is rotation. You'll always know which bottle of oil is the oldest if they all have the date of purchase on them.
Second, you'll find out how long things last. Because I date my stuff, I know I can use canola oil that is 4 years old and it will be okay as long as the bottle was sealed the whole time.
Third, you'll find out how long it takes you/your family to use something. When you know how long something lasts at your house, you can calculate how many of that item you will need for a 3 month, 6 month, year, or longer supply. Keep in mind that items like oil/flour/shortening you will use more of in a survival situation as you won't be supplementing with convenience foods at that time, so better to overestimate than underestimate. AND items like shampoo you will likely use less of than you do now (bummer).
Here's my current shortening can. The red date is the date I bought it and the black date is the date I opened it.
Some things like toilet paper can't be sharpied, so a pencil and paper to keep track of those items would work. DO keep a notebook with your calculations in it--this I have not done and I wish I had (I guess I honestly thought I could keep track of it all in my brain . . . duh!). So I'll be re-dating some items I know I have already calculated and writing it all down for my notebook this time! Happy Marking! :)