Every situation is different, so you won't get a useful list of questions. But what investors want to see is how you are going to make them money. One of the easiest places to slip up is forgetting that investors don't win just because your company grows or is successful; you also have to orchestrate an exit strategy so they get money returned on investment. They want to turn your company over, not stay with you forever. Different investors have different priorities, so make sure you do your homework about the specific investors you talk to. Most of them have websites indicating some of their opinions and preferences.
If I had to summarize, meaning guess, I'd say that the management team, its experience and track record, is extremely important. Investors reduce risk by betting with people who have been there before. And then the obvious: differentiation, growth prospects, valuation and everything that makes the investors money.
Best of luck to you.