One of the biggest early missions that you'll face in Baldur's Gate 3 is a mission to infiltrate a Goblin Camp that is celebrating a raid. You're there to find and rescue a druid called Halsin that has been captured by the Goblins during their raid, and once you find him, he'll task you with killing three Goblin leaders.
You're given the option here to bring Halsin with you if you want, but if you do then you'll be in combat with the entirety of the Goblin camp the second that they see you, so if you want to be quieter about it then leave him behind.
Killing Priestess Gut
Priestess Gut is the leader who takes the least thinking when it comes to working out exactly how to kill her. If you walk up to Gut and talk to her, she'll chat with you and realize that you have a tadpole in your head before taking you through to a room so you can chat alone.
Once you're in there, jump her. Shut the door first, but then jump her. If you can kill her specifically BEFORE she decides to call for reinforcements, then you can just leave and move to the next target. Otherwise, you will have to battle through a swarm of Goblins, which could take a little while and cause trouble for under-leveled or underprepared players.
Killing Dror Ragzlin
Dror Ragzlin will take the longest to beat. It's here where we'd recommend grabbing Halsin if you have trouble since Ragzlin is surrounded by a ton of allies who will make your life a living hell. You CAN stealth this fight if you specifically have a party created for that, but otherwise, take Halsin with you as you chop Dror to pieces.
Killing Minthara
There are a couple of ways to kill Minthara. If you want the loot, then you'll have to take on every Goblin in the room as there's sadly not really a stealthy way to kill her and still loot her. Make sure that you don't position your characters near any cliff edges or they'll be pushed to their doom.
If you don't really care about the loot, then you can tell Minthara that you want to attack Emerald Grove. She'll walk across a bridge in the middle of the room which you can shoot to destroy the bridge and cause her to fall to her death.
Alternatively, you can actually just let her go to Emerald Grove. She'll get there and expect you to betray the Tieflings inside, but you can instead side with the Tieflings to fight her and her army. The major downside here is that there's a decent chance somebody dies who could be significant later in the story, so only do this if you're sure you can beat them.