Baldur's Gate 3: 11 Tips & Tricks The Game Doesn't Tell You
5. Examine Enemies To Get The Upper Hand
They say that knowledge is power, which is especially true in Baldur's Gate 3 as a great many characters have resistances against certain damage.
So before you attack make a point of right clicking on the specific enemy and choosing to examine them. You'll be faced with their character sheet which shows their ability scores, resistances, and other useful pieces of information.
This will prevent you from using attacks that cause them half-damage or spells that require a saving throw that they are proficient in. Using the 'sacred flame' cantrip against an enemy with a high dexterity score will be next to useless, for example, as it requires a dexterity saving throw to avoid.
If they have a low wisdom score then use another spell or cantrip that requires a wisdom saving throw, as this will have a greater chance of succeeding.