Airmen25 - it's been my experience the less confident the pilot, or Captain, the smaller the tolerance window they have. It's a tough situation to work under. But it can also be viewed as a challenge. If you can stay within the 'box' that keeps them more relaxed you'll operate better as a team.
I wish there was a perfect answer for flying with a difficult or even unreasonable Captain. Part of experience is learning how to 'read' the Captain. No, they don't have a license to be Captain Quegg(google 'The Caine Mutiny') but each crew, or Captain, is slightly different. A good Captain will adjust just as good FO's adjust to the dynamics of a different crew.
You mentioned that you were on a trip as a second FO. Watch the more experienced FO's when you're the second FO. It can be a great learning experience. I'd pay extra attention to see how the Captains, or more experienced FO's, deal with situations that are slight different than standard operations. That's the value of experience, turning potentially interesting situations into anticlimactic events.