Ask HN: Best way to prepare for an Onsite interview at a Startup?

I'm a New Grad (as of 2wks ago), and I've gotten pretty far in pipelines but never to an onsite with a company. I don't come from a solid DS & A program so I've been working on my own. I've been able to schedule an onsite with a startup two weeks from today. The onsite was described as a mixture of talking about my background, technical interviews, and whiteboard coding. In looking to maximize the possibility of getting an offer, what can I do to prepare that would be very beneficial? Also since it's a startup, what type of questions would I be most likely see in an onsite interview?