Prepare with pilots jobs network (compass)
Fly a bit without flight directors at work (sim screening)
And BE YOURSELF (interview)
Also for the interview, think about a couple of flights you've had in the last couple of years, that stood out from the other normal ones. Good/Bad colleagues/situations etc.
They will ask you for details, when they ask you questions in the interview.
And also not to be forgotten. Eat a big breakfast each morning. There won't be much time for food or drinks during the assessment.
That all helped me. Prepared about 3-4 days in advance for the whole assessment.
Good luck