Missing Inventory - What are your Best Pracises to prevent this?

I've been working with amazon for about 2 years now

When i started out i made some mistakes which lead to missing inventory - totally my fault, however becuase of that i have bolstered my practises to reduce missing inventory as much as possible

But it still happens significantly enough to damage my bottom line

My question is...what are your best practises to REDUCE this happening as much as possible, I've even broken it down to sending 1 SKU per BOX - and STILL, it partially goes missing, which I'm confused about . I add labels to things even when it says "you don't need to label this" just to avoid confusion at all

I'm thinking I need to literally video me packing each box (which will be a big resource drain)