What I'd want:
1) A Constitutional amendment eliminating the Electoral College and stipulating that the President/VP are elected by majority of the popular vote. And in another section, it will require that nominees be chosen by the voters in a national primary election.
2) A Constitutional amendment requiring Congress to set a spending limit by Presidential campaigns. The baseline will be the total spent in the Presidential election immediately before the amendment takes effect. The limit cannot exceed 10% more than was spent in each subsequent election. And in another section, state legislatures are required to apply the same rules to state elections for governors, senators, and House reps.
3) A Constitutional amendment requiring that donors of $100 or more to any candidate for national or statewide office be identified by name, address, amount donated, and recipient of the donation. Any PAC or other other organization making a donation must similarly identify its members, and the amount each member contributed. (This is the Citizens United negation amendment.)
4) A Constitutional amendment requiring states to draw House districts only in a manner that equalizes population in each district as much as possible. (This is the anti-gerrymandering amendment.)
These would be a good start.