http://www.blackjackinfo.com/bjbse.php
Some of the splits in this basic strategy chart are very aggressive and I wouldn`t do them even if up a lot.
Like splitting 8`s against a 10 or A or splitting 2`s or 3`s against a 2, 3, or 4.
Hitting a 12 against a 2 can go either way.
I like to hit it but if someone else stays with 12 and the table is basically playing for a bust, I am not going to try to be a hero and risk killing everybody.
Hitting 12 against a 3 is aggessive and I sometimes do it but usually don`t.
I will sometimes hit a 13 against a 2.
Most of basic strategy is basic common sense but there are several moves that are borderline and could easily go either way and I play them according to how the flow of the game is going and how I feel at the time.