Yes, definitely try to get a recommendation from a YC alum or partner. It's easier than you think, just hound them (be nice and polite thought) on Twitter and try to meet them for coffee (ideal) or over Skype to ask for advice. Think of it as a pre-interview, they'll ask you a bunch of good questions and will help you to come up with the answers. If you are personable and passionate enough, you'll very likely get a recommendation without even asking.
Also, practice for your interview with someone else (there are some good resources out there with sample questions), that practice will help you feel calm and confident for the real interview.
Last, but very crucial for your startup nonetheless, focus on showing your ability to grow/gain traction. Even great ideas are not that valuable by themselves. And having 10 clients with a shitty product is way more impressive than a great product with 0 clients.
Also, practice for your interview with someone else (there are some good resources out there with sample questions), that practice will help you feel calm and confident for the real interview.
Last, but very crucial for your startup nonetheless, focus on showing your ability to grow/gain traction. Even great ideas are not that valuable by themselves. And having 10 clients with a shitty product is way more impressive than a great product with 0 clients.