Record every item once
For each item: a clear name, a category, a serial number if it has one, a photo, its value and where it lives. A photo matters more than you expect. It settles arguments about which of the three identical monitors is meant.
Name things the way the crew does
If everyone calls it the A cam, the inventory should say Cinema camera body A, not the product reference. People search with the words they use on set.
Give every item a home
Shelf, cage, rack, bay. When each item has a written location, returning gear after a shoot takes minutes and the next prep starts from a known state.
Group by kit
A lavalier kit is a transmitter, a receiver, a microphone and a pouch. Track the kit as one line with a note of its contents, and check the contents when it comes back.
Check out and check in
Before a shoot, list what leaves. After, tick what returns. The gap between the two lists is your missing gear, found on the day rather than a month later.
Review twice a year
Update values for insurance, retire what is broken and note what is rented often enough to be worth buying. In CrewDesk the inventory holds categories, locations, photos and value for exactly this purpose.
Start small
Do the camera department first. It is the most valuable and the most borrowed. When the team has seen that returns are faster with a list and photos, the other departments follow without a memo.
Go further
The equipment checklist gives a list by department and a check-out routine.