1) I think that Medius is alluding to a "germaneness" clause. Where any and all amendments must be germane to the original legislation, and original bills may not modify more than one section of law. I agree with this.
2) Terms and limits for all legislators and President. 4 year terms, 2 term limit, for all. All elections held on a single day. No political contributions (political parties, candidates, PACs, etc.) except for 1 year before an election. No political advertisements for/against political positions except in the year before an election (exception made for ads for/against specific issues). This would cut down on the perpetual campaigning and allow lawmakers to actually do their job, without fear of falling behind their competitors.
3) Return the appointment of Senators to state legislatures. This would mean that one chamber would be able to enact laws for the good of the country, without having to much worry about public whim (face it, most people have no idea what most legislation says, but they sure become outspoken about what they THINK it says - "Keep your government hands off my Medicare"). But, they would still be somewhat accountable (our state reps would hold them accountable), so they wouldn't get out of hand.
Those are my main three. I might put in something about repealing the 16th Amendment, but I really don't know the ramifications of that. Just that I like it on a philosophical level.