With our current system of Winner Take All voting, we commonly here people say that voting for a third party is "throwing your vote away".
With an Instant Runoff format, a voter would chose who they want, and also who they want in the event their first candidate doesn't receive more than 50% of the vote.
This would allow voters to choose the candidate they really want without the stigma or fear of "throwing your vote away".
While there are many more changes that should be made to make the election system more equitable, modifying the voting process to an instant runoff format would have the most immediate impact while also being the most bi-partisan (and hopefully tri-partisan!)