• Impose Congressional term limits
• Repeal the Seventeenth Amendment, returning the election of Senators to state legislatures
• Impose term limits for Supreme Court Justices and restrict judicial review
• Require a balanced budget and limit federal spending and taxation
• Define a deadline to file taxes (one day before the next federal election)
• Subject federal departments and bureaucratic regulations to periodic reauthorization and review
• Create a more specific definition of the Commerce Clause
• Limit eminent domain powers
• Allow states to more easily amend the Constitution by bypassing Congress
• Create a process where two-thirds of the states can nullify federal laws
• Require photo ID to vote and limit early voting

I'd also like to see one clarifying and cementing the 2nd amendment, since it's apparently not clear enough as is.

Source