Vote. You don’t have to vote for Biden or Trump, you can write in a vote or choose a third party or independent candidate on the ballot, if your State allows it. Not for the reason of making practical change, because it won’t in a two party system, but to show the analytics, media, the ruling power that you don’t have to vote for the lesser of two evils. Anyone that says otherwise does not know what democracy means and supports a broken system through enabling. Local votes ate more important IMO, always vote for that. The more informed you are, the less likely you are to support a broken system.