So you want to work in a startup?
blog.startuplife.in
blog.startuplife.in
I've only had two positions related to Product, so the only (limited) advice I'd have to add from that perspective is that, you should understand the landscape very well and keep very up to date with the news. This will help you to have a high-level understanding of where the company and its product stands with regards to the users as well as competitors. Providing high level analysis and feedback on the spot (during an interview) speaks louder than anything you can put on your resume.
Thats a good advice on keeping up what's happening in the landscape and in your professional domain. It also helps you to develop taste what's good and what is possible and show that you're enthuastic about your profession.
Also a good tip is attend hackathlons, RailsRumbles or others contests, or just doing other couple of small fun projects during a year. You might do well and gain some reputation. Atleast you'll end up with a impressive resume of projects that you can actually 1) show 2) talk everything about them since they're yours (not under some company NDA).
Congrats!