We don't have rosette restaurants in the U.S so I'm assuming it is the same as Michelin stars. I just did a bunch of stages at Michelin star restaurants this week including a 5 day at a 3 star place. I would say don't be intimidated. Work extremely clean, fast but diligent, show that you have a great attitude. Never lean. Don't speak too loud. Call everyone Chef. Don't slam any doors. Always be moving. It is hard to train someone to be clean, it is even harder to train someone to have a good attitude. From what I've experienced if you can do both those things, and also have a decent cooking foundation then they will hire you. Also, don't drop anything :). Idk, thats how it is here in the U.S things could be different in other parts. The 3 star place I staged at was extremely quite and focused.