I've been dropped in the deep end on a couple of occasions now with teams and travel and working with athletes I'm not familiar with. Here's some notes on what you need to work out with the athlete before race day :

When working with a new rider on tour, the following need to be discussed between coach(es) and the rider :

• "What do you need on race day to perform at your best?"
• Pre race briefings – what do you need? Focus/humour/leave me alone?
• "Debrief after races? If good result? If bad? When/how?"
• "Food/drink/suppliments"? What/When/How/Why? (legal?!)
• Warmup and cool down support?
• Logistics?
• Any special needs?
• Equipment, any quirks? Power meters? Special gears? Tyres? Pressures? Can do own gear changes etc? Spares?
• Push starts? Ok with pushing on body? Lifting on start lines? Ok with hand on top tube? Check with parents as well if a junior?
• After racing – pack up protocol, a rush? Talk with other competitors? Allowed time for socialising?
• Who packs up equipment? Any special requirements?
• Travel – any after effects, and travel medication?
• Medication/illness – anything?

What not to do?

Do NOT challenge an athlete's training or race choices.  You're there to get the best out of them, not to change them. If they're working with another coach, it is NOT your role to change what they do on race day.

There's more, but these are some key things to start with.