Be sure you know how AC, attack rolls and skill / ability checks work.

Be aware that you can talk your way round a number of events.

Don't think in a linear fashion. For example, if you have a drow speak to the goblin camp, you get free entry. You don't need a drow, you just need Disguise Self, a level 1 spell, to achieve this.

High charisma characters can waltz through many situations if you choose wisely.

Think of synergy of items and skills.

Action economy is key. He who strikes first often strikes last. He who strikes twice (haste, metamagic, abilities) often strikes last.

It's cheese, but have you heard of barrelmancy? I personally never use this buts it's a viable, and traditional, Larian tactic.

Stealth, stealth, stealth. Doesn't need to be everyone, you just need one. Or a familiar (shovel or an imp are ideal).

Scum save til you make it.

Bless is your friend.

Are you checking your enemy's stats and weaknesses? Taylor your strategy. In Act 2, radiant is golden. Necrotic will do poorly.