The salary of all elected of officials should be reflective of, or equal to, the average income of their constituents.
The president makes as much as the average American.
Congress and the Senate makes as much as the average citizen of their state.
Local governors make as much as the average citizen in their city.
This creates a direct financial incentive to best represent what is best for the people they represent.
Also the financial status of any elected official must be reported as of their election and all subsequent years while in office. This can be done in the same method as taxes, or in a more streamlined income statement-esque form. This allows transparency in how much money they are making while they are in public service.