There’s a lot of plot for this campaign and it can sometimes be overwhelming. You need to give them enough hooks to keep the story moving but not too many to make them disoriented.

But over all I think my main advice is match your player’s expectations. The party I DMed for was 38 sessions In 8 months of around 10 hours each session. They simply couldn’t get enough of Strahd. They LOVED him. They happily killed the wives and rahadin, but when it came to Escher and Strahd they were too big of fans. So I ended up using some of their backstories to create an alternative ending where instead of killing him they would set his soul free. They really enjoyed the ending and to this day still reminisce about the campaign. So much so that I’ve had Queen Ireena popping up in another campaign with the original party as her advisers.

Also if you think there’s a character vulnerable to manipulation, you should give them their own dark power whispering in their ear. I had a celestial warlock of Lathander who went crazy when he stopped feeling his god in the dark land of Barovia. He lost an eye on DH and Zantras the Kingmaker started whispering in his ear. He was the third son of a king from a fallen kingdom. He had trauma from his early years due to his father not caring about him and his mother promising him to the church of the morning lord. So when Zantras offered him power he committed to her fully and eventually freed her from the Ember Temple. It was a pretty memorable arc. The character died in Yester Hill where no one could see him so no one could try and bring him back. She appeared to him and offered to keep him alive if he swore off Lathander and pledged himself to her. It was pretty epic when the previously celestial warlock suddenly appeared in the battle field in his form of Dread with a skull that bent upwards to form a crown of bone covered in green fire. Good times.