State Election Comissions at the top, local election boards at the bottom. Every stage from top to bottom needs close scrutiny with a mechanism to be put in place that guarantees the ability for every voter to verify that his vote was counted as cast.
Every vote examined and adjudicated by a balanced partisan team. Take whatever time is necessary to get it right. Paper ballots with a serial number both visible, watermarked, and micro-printed.
Basic civics test required of all who vote or run for public office. Test for public office holders must require at least three essay questions to be answered in their own words. 1.) What is the difference between a democracy and a Constitutional Repiblic, 2.) What is the difference between a citizen of the USA and a citizen of the world, and 3.) What is the difference between a right and a privilege?
Where the heck are you going to find that kind of team?