Timing is a very important tactical concept which most people seem to ignore or not think about. Tempo can be seen as a sub-topic of timing, dealing with the flow and movement of the game. A mastery of these is necessary to ensure that your units are used the most effectively, and greatly influence your chance of winning.
I will break down timing related tactics into the following sub-topics:
-Initiative Order
-Interaction between your initiative order and the enemy's
-Manipulating/taking advantage of the turn order
-Momentum in battle
Each sub-topic will have its own post. Warning: walls of text.
TLDR: be aware of timing and tempo. It heavily contributes to winning games.