Learn the Hit/stand and Hard Double Down Indexes. Soft Doubles have little value to be gained via indexes except A8 vs 4,5,6 and A9 vs 5,6 if you choose to do that one. Splits also have little extra value beyond basic strategy but I'd learn 99 vs 7, when not to split 88, and 99 vs Ace has some value in high counts. Also 44 vs 4. 10-10 splitting has strong value but obviously can get you tossed out. Many of the double down plays vs dealer 2 you should add a few points to the regular index and probably should never double 10 vs 10 no matter how high the index gets.
For Surrender learn 16 vs 8,9,10, Ace, 15 vs 9,10, Ace, 14 vs 9,10, Ace, 13 vs 10, along with Hard 17 vs Ace (h17), 88 and 77 vs 10.
Generally you will want to learn more positive indexes if you table hop a lot. If you play pitch games with a fairly tight spread the negative indexes become quite valuable. Regardless, most of the Split and Soft Double indexes have relatively little value (i.e., basic strategy gets you most of the value from those).