Labels are a big key. Expiration dates, contents, special instructions, etc are all good.

I'm a big fan of excel spreadsheets. Kinda dorky but you can use them to both keep track of what you have, total up what you have and keep stock fresh.

You can also consider using a to-do list or calender on your computer/ipad/phone with pop up reminders triggered on a specific date. Clearly these won't be all that handy in the middle of a event but they can help you stay on track before any sort of SHTF event.

Organization is key IMO. Not knowing where your preps are, or their state, is only slightly better than not having them at all.