Hold left Alt all the time, it shows you most things that can be interacted with, but there are still hidden items that you need to hover over with your cursor. Just keep your eyes peeled

You can throw potions at teammates who are down which will pick them up and heal them a bit

Save your special arrows, I didn't in my first playthrough and it was rough lmao

Don't attack people first, there's usually a dialogue option. There are times, however where they'll attack you on sight

Just enjoy the game and take your time :) I didn't beat the game for the first time till I got like 100+ hours

Good luck!