The main thing is that if you beat him in a fight, be sure you /don't/ penetrate him. Mutual masturbation is fine, just 'do not get a black heart'.
Then besides that, it's just 'generally don't be a huge jerk to him', even when he kind of deserves it. When he insults you, roll your eyes but don't necessarily snap back. Help him out when he needs some herbalism while building up Bareshade. Don't tell Torben about his duplicity.
The meetings, I will emphasize, are not particularly 'friendly' yet haha, just a lot less hostile than they were at first. He's mellowing.
...now if you're a bottom or female, another option is to just cooperate with him and let him be in charge, in which he will presumably be a lot happier with you quickly haha.
Just make sure you don't get a black heart with him and hey.