Take Your Time
Take your time in approaching enemies. This doesn’t mean you need a solid game plan written out before charging into a stronghold, but don’t just go in sword a blazin’. The best thing to do is take out the archers posted in the high points of a stronghold. Archers are the eyes of the encampment, and they also do some decent damage. Eliminating them right away with a well placed arrow to the head or a stealth kill will save you a lot of trouble later when you’re stirring things up at ground level.
Making the rounds killing archers is also a good way to get acquainted with a stronghold before beginning your objective. Strongholds aren’t small, so it’s a good idea to know where your exits are, where you can lay traps and where the captains are hanging out.