Learning Indices for Plus/Minus Count

I know my Basic for the Casino I play at. I can count HiLo with no errors, and Havles with some errors. An suggestion for learning Indices for Plus/Minus Count? I've read to only worry about -1/6 because on minus counts your going to be betting your minum and 7 or better true counts are not going to happen that often.

I am looking for a way to teach myself keeping it simple. ie flash cards.
I've used flash cards for learning BS. 10+6 on front,

16=2-3-4-5-6 S OWH(other wise hit)BS=2-6 back.

So when I have 16 I say in my head 2-6 OWH.