Number one would be transparency in government. While there are some secrets that must be kept in the interest of national security, our nation is a republic, and if it is going to be true to the ideals of a republic, it has the obligation to keep the nation informed. I don't mean inundating the public with needless facts, statistics, and information so that the true bottom lines are being concealed, but to keep all of that information public while still sending regular concise and (relatively) understandable updates to all citizens. All campaign contributions, lobbies, and other influences into the political process would have to be included.
Number two would be a greater investment in arts, sciences, and exploration. I don't just mean monetary contributions to big businesses that talk about making accomplishments, but to set both specific goals and general "prizes" for individuals and companies to try to achieve, giving both aid and incentives to do so. This also means investing heavily into our education programs to ensure that our upcoming generations have the knowledge and skills necessary to reach those goals (and to understand the aforementioned governmental updates).
Number three would be heavy investment into our nation's infrastructure, whether that be roads, the electrical grid, the pathways of the Internet, hospitals, schools, courts, prisons, or our water systems. This investment could be directly done through the government (like Eisenhower's Interstate projects) or through selected businesses, but assurances of quality would have to be maintained (see the above transparency rule).
... This post is most likely already past most people's interest, and it is later than I thought it was, so I suppose that I'll just leave it at those three for now. For the most part, they are the main three that concern me in my voting anyway.