Are you immediately running into battles or are you taking the time to examine the environment and enemies before initiating battles? Obviously it's not always possible, but I usually spend a few minutes to plan some things before starting a fight.

I look at the environment to see if there are any items I can use to my advantage (barrels, chasms, etc.) or any optimal places to position my people (e.g., up high and out of sight for my rogue).

I also examine the enemies before hand to look at their strengths and weaknesses, and I change out my prepared spells accordingly.

In a game with dice rolls, it's inevitable that some things will come down to luck. But I do think there's still a lot of "tactical" planning to be had both during the battles but even before the fight starts as well.