The one most important change would be to simply allow people to vote for two.
The two-party system would become a more-than-two-party system, all on its own. No more lesser of two evils. No more "don't throw your vote away." No more spoilers. If you could vote for two, you could vote your conscience AND vote for a mainstream candidate. No more top two, who only need to destroy the other one to win. More positivity. More voter participation. More expensive for the powers-that-be to control them all. More democracy.
See the summary page for the rest of my Presidential election plan. http://constitutionrepair.blogspot.com/2016/10/summary-of-presidential-elections.html?m=0
