I am of the opinion that there needs to be a greater distinction between federal elections and state elections. Federal elections should follow federal rules, states can do what they want within the confines of the Constitution.
In particular, elections for federal office (President, Senator and Representative) need to have the same rules across the US.
1) Separate voting rolls from State rolls
2) Voting rolls cleared/purged of all registered voters on March 1st following a Presidential inauguration.
3) Individuals must register in person and provide proof of citizenship and residence in order to register
4) Registration closed 30 days prior to an election
5) Mail in ballots only to those that request
6) No registration or voting allowed for those that are wards of the state (prisoners, mental ill, etc).
7) Drivers license change prompts an automatic notification of change of residence to the “losing” state and removal from their voting rolls.
8) No provisional ballots
Some elections are for federal offices, but the states hold these elections on their own.
Constitutionally, the only federal "office" that had direct elections set up by the Framers were House elections. Elections for Electors to the Electoral College were transitory, as these were not for federal "officers" serving terms. The Senate did not have elections until 1913, but even these were state-by-state elections.
-PJ