Having an accurate inventory of your preps is very important. It lets you know exactly how much of a particular item you have and
what you need more of. It also helps with rationing and theft(although theft should not even be a factor)
The military uses classifacations of supplies to make items easy to
identify when they are in containers or being stored. Of course as always use whatever system works best for you.

These are Army
Classes of Supply
Class I - Food, rations, and water
Class II - Clothing
Class III - Petroleum, oils, and lubricants (POL)
Class IV - Fortification and barrier materials (Barbed wire, pickets, sandbags, etc.)
Class V - Ammunition
Class VI - Personal Items (Hygiene, alcohol, tobacco, etc.)
Class VII - Major End Items (Vehicles, radios, tanks, weapons, night vision, etc.)
Class VIII - Medical supplies
Class IX - Repair Parts
Class X - Miscellaneous supplies