I usually know what moves I will use before my opponent's turn has ended, so I'd like to be able to queue my actions on my opponent's turn, to occur immediately when my turn starts.
I was thinking something like 4 boxes at half the current box size, choosing an action on your opponent's turn adds it to a box.
On your turn, the game cycles through the boxes, until you're out of turns, and if one action is out of range, it moves to the next box.
Clicking on an a box empties it.

And on the subject of smaller boxes, I think all the action boxes should be half the size, so you can fit them all on the screen at the same time