Ballots only being validated by the voter's fingerprint is the best answer, IMO. Few people would commit voter fraud when their fingerprint is on the ballot identifying the person committing the fraud. No fingerprint = invalid ballot. Fingerprinting must be required in order to register to vote. Citizenship must also be validated at the time of voter registration also.

No "voting machines" and no internet connectivity of any kind allowed. Mail-in ballots restricted to overseas military and very ill patients or seniors - requiring doctor's verification. Stop "early voting" altogether - citizens vote on Election Day and all ballots must be counted by the end of Election Day.