I bought some of those *tiny* "dots" in different colors at Office Depot - they're like 1/4" or so and have 4 different colors. I stick one on my cart and put a control number on it...
#1 = 8mg cinnamon roll filled on 4/21 or
plain green = 8mg (if the cart is labeled with the vape flavor but wrong mg)
I haven't had trouble with them falling off and it's better than trying to remember what color tip with what color cart on what color battery = 4mg cinnamon roll
You can use whatever symbol you want or need to remind yourself what's what

I also apply them to the top of the bottles (they fit like a glove) and know a yellow dot is 0mg, blue is 4mg, etc., etc. and a dot in the middle will add 10 or 11mg to get 11mg & 18 mg. That's as high as I go so adjust accordingly