The ultimate answer is to push as many people to vote as possible. This actually serves multiple useful purposes.
Attempts at voter fraud will be more noticeable if a large percent of the population gets out to vote. Sure, there will be people that are sick, absentee ballots from military members, people who recently died, and the like, but if a large majority of people actually get out and vote, then there is less room for fraudulent votes before we get to the point where that spillover becomes very noticeably fraudulent to the point of absolutely requiring an investigation.
If there are more legitimate votes, then voter fraud becomes less reliable. A static batch of votes holds a higher proportion, and therefore a higher value by percentage, in a smaller pool of votes compared to a larger one.
If more people go to the polls, it will be easier to pick out certain types of voter fraud. Particularly vote manipulation by way of paper ballots destroying or disposing of large portions of paper ballots is difficult because, again, a small number of tossed ballots has less effect on a larger sample, and falsified ballots will show up in larger numbers during a recount, electronic voting machines more people will notice "glitchy" machines and start demanding paper ballots. Extra bodies being bused around might be harder to spot, unless they start getting visibly nervous in line, but more people mean more eyes and cameras, so it might be easier to catch them at multiple locations.
Even if you don't think your voice matters, even if you don't think that it helps, and even if you think voting in this retarded duopoly system is pointless, you should convince as many people as possible to research candidates and vote in primaries and elections. Even if voting our way out of this quagmire is impossible, (((they))) will never expect a large majority of people to vote, and it will throw a massive wrench in the works that will force voter integrity laws to the forefront of every major issue. Since it's entirely undesirable to push voter integrity issues into the limelight, which will bring decades of voter fraud into the mind of the public, pushing the idea that it's every American's right and duty to vote is imperative to changing the political landscape.
True, people have cried for years about voter fraud, even at the highest levels of power, but nobody ever pushes for a recount. The few times recounts have happened, even, those cases usually get shunted to secondary or otherwise unimportant levels of news in favor of more sensational or easily manipulable news stories. If this comes to the fore in a grand fashion, to the point where it becomes impossible to ignore, then politicians will be forced to make very difficult decisions to keep their seats of power, and forced investigations will reveal the truth or show their true colors.
Get out and vote!