for keeping track of actions, i keep a running count as i play my cards from left to right. if i play a village, i add 1 to the number, a terminal i subtract one from the other, and a regular cantrip (i.e. market, spy), the number stays the same. i find it helpful to say outloud as i play cards in engines decks how many actions i have left.
for KC, i make a tree. so if KC a KC, then i branch off 3 ways from the most recent KC, and play each action 3 times. if i play another KC, i start a new branch, and work my way backwards as i finish that KC.
for minions, it can be easy to forget which ones i play for money and which i play for the discard. for this i still play my actions left to right, but the ones i play for money i play them about an inch higher, so when my turn is over it is easy to count up how much money i accumulated from the minions.