This post is in response to the question posed by @dbruce: "In the U.S. we have separation of powers to prevent one branch of the government from becoming tyrannical and federalism to prevent the national government from being overbearing. What other anti centralization and corruption measures could be put in place?"
The most important thing that anyone can do when trying to defend against tyranny and a centralized government is to never give the government too much control in the first place, or increase the power of states. Keeping the federal government's power at a minimum is the first step in guarding against tyranny for even if a dictator type person got in power, they would still have limited to no influence on the citizen's lives. One way we can take away some of the government's power is to remove government restrictions on businesses and corporations and medical care. These two large aspects of American life are heavily controlled by the government and therefore gives them power over American citizens. The removal of these restrictions, regulations, and monopolies on healthcare would open up the market and make people rely on each other more, therefore stimulating the economy while also guarding against a central plan. The second way is to increase the power of the state governments, which would make it much harder to install a central plan in American due to all 50 states having slightly different laws and regulations. Personally I think the latter option is the best and more reasonable way to defend against tyranny in America. The state governments are plenty qualified to impose original laws on its citizens while also being more in touch with their citizens than the federal government is it touch with its citizens.