A lot of what needs to be done is making sure that the Harris win is large enough that you can’t easily claim that a handful of ballots should be tossed and change the outcome. That means:
- Check your voter registration — part of the Republican strategy has long been invalidating registrations so people can’t vote
- Volunteer — nothing in the world quite like talking to people.
- Donate — money is used for everything from ads to voter turnout operations
- Organize; be prepared to turn out with others in your community to actively object to any effort to ignore your votes
It’s called a “faithless elector” and what happens depends on the law of the state the elector is representing. Some states void the vote without penalty, some void it with some penalty, some allow the vote but with penalty, some allow the vote with no penalty, and some have no law at all (which seems like no difference from allowing with no penalty).
It’s entirely conceivable that enough faithless electors from states that do not void the vote could swing an election, though there’s never been enough to do so before.