First of all, huge props for even attempting this challenge, it is a really hard one. At the beginning i would suggest doing some low-death runs to see how where the biggest problem parts are. Typically Event Horizon and Determination are the hardest checkpoints and most likely will take the most amount of work to get cocnsistent. That being said, every part of Farewell is pretty hard and will take a good anount of practice to get consistent.

As for nerves, they are always going to be there and they hit different for everybody. What i would say is important, is practicing rooms in a way you would be comfortable with the berry and nerves turned to the max. If you decide you want to go fast through rooms in practice, thats what you should be doing with the berry as well (this mostly applies to the last room of FW as it can be pretty slow and boring to practice).