Dear new consultant,
Congratulations. You've taken a job that will teach you, very fast, three things almost nobody else gets to learn in their twenties: how to read a business in an afternoon, how to disagree with a senior person without losing the room, and how to write a paragraph that holds up under interrogation.
Those three things will pay you for the rest of your career. They will also, occasionally, ruin a vacation. Both are true.
A few notes from twelve years out.
Be the person on the team who reads the deck out loud the night before. There is a specific, recoverable category of error that only surfaces when you say the words. You will catch them. Your seniors will notice.
Take notes by hand, at least for the first year. Not because handwriting is magical — because the friction of writing slowly forces you to translate, and translation is what consulting is.
Ask for the boring assignments. The interesting ones come with senior partners attached, and you'll be ornamental on those. The boring ones are where you'll actually learn to build a model, or write a section, or talk to a client without a script.
Finally: keep one book on your desk that has nothing to do with business. The job will try to crowd everything else out. Don't let it. The most interesting consultants I've worked with are interesting outside the slide-deck.
Good luck. — J.