The itinerary is super important. Show them a day-by-day plan, even if it's tentative. It demonstrates your purpose. For financial proof, aim for at least 3-6 months of bank statements showing sufficient funds. If someone else is sponsoring, you'll need their bank statements and a notarized sponsorship letter. Also, consider checking out this post on
planning a 2-week Europe trip on a tight budget, it might give you ideas for your itinerary!