On inventory

As work comes in, I have to constantly keep my inventory in check. By asking myself questions, I'm starting to feel close to getting a handle on things. But lately I've been realizing that I need to include time into the equation, not just supplies. Anyway...

First there are personal items that only I can follow through with:
Make sure my inks aren't low.
How many more days can I go with this box of (premade) needles?
Do I have enough disposable liner tubes?
Have I prepared enough paper towels for tattooing? (separating individual sheets into a pile)
Do tubes need to be scrubbed, and do I have enough for a steady flow of traffic?
Keep the drawings coming. (this deserves its own post)
Are my deposits in order? (our customers leave $20 deposit for appointments - which, in turn, goes towards the price of the tattoo)

Then there are shop related items, that the shop owner covers, but I use:
How is the supply of paper towels?
Am I topped off with Green soap, distilled water, MadaCide, and alcohol?
Check the supply of ink caps, dipsticks, dental bibs, and razors.
How is the supply of paper towels?
Are there enough gloves, or do I need to jump in back and get another box?

Now my only difficulty is figuring out how to add new items to test into the list effectively. This means not buying everything at once, rather spreading it out and slowly mess with new stuff.