Before each move you must scan for any fresh opportunities to play a tactical combination. Usually both sides will have a number of slight edges in different aspects.
All kinds of imbalances can exist in a position. One player or the other may have an advantage in material, structure, initiative or space. Someone could have a passed pawn or a Bishop pair.
Usually the little imbalances even out the game and it's about who can make best use of their advantages. Figure out whether you have the dynamic advantages (time, initiative) or the static advantages (material, structural).
The player with the dynamic edge should have tactical opportunities. The other player must defend against any possible tactical shots and try to retain his static advantages into the endgame.