Everything! Each person you speak to will have their own ideas about what issues are most important for us here in Guernsey, and their own view about how those issues should be addressed.
You don’t have to be an expert on everything, though. If you’ve been in the States before, you’ll be expected to know more than if you’re a first-time candidate. But even returning Deputies get to say “that’s not a topic I’ve had much involvement in, so I would need to do more research”, or “actually, we’re looking into that at the moment, I want to see what the evidence says.”
If you can’t tell people what the solution to a given problem is, then try and tell them how you would go about solving it, or what kind of things you would be looking for in a solution.
And also – don’t forget to listen. People who ask you about a given topic are probably doing so because it’s something they care about. It may well be something they have a professional background in, or have thought about carefully themselves. Don’t be afraid to say: “this is how I think I would approach it – but what would you do?” Take the opportunity to learn from the people you meet, as well as to share your views.