Don't be afraid of friction. Friction, or even unpopularity, can be the price for trying to change the status quo. If elected leaders view their job as simply finding the center of gravity on every issue, they might retain their popularity -- but all they will have done is encapsulate public opinion, not lead it. On the other hand, if political leaders want to shape a new consensus, they have to risk alienating those who support the current status quo. Reagan knew that his job was not to make everybody like him, but to help move America in the right direction.
Focus on a few key goals. For Reagan, his goals were to confront Soviet expansionism, reduce the tax burden and place limits on the size of government. He proved to be highly successful on the first two goals, and only abstractly successful on the latter. The federal government expanded substantially during Reagan's presidency, even if we allow for military growth. But let's not confuse an inability to implement goals with the desirability of the goals. Reagan did change the debate about the nature of government and the open-ended expansion of the welfare state.
Don't confuse expertise with leadership. As a political leader, Reagan was masterful. He combined a clear sense of purpose with natural stagecraft and the charming occasional idiosyncrasy. He also understood that as president, you didn't need to be an expert, you could hire experts, and he did.
Be upbeat. People want to believe in their leadership, believe in their country, and believe in themselves. A president has to paint a picture of a better country and come up with the program to help get us there. There is an old saying in politics. "People don't care what you know until they know what you care."
