The first “action” should be to sign The Pledge to Safeguard the Election (https://sign.moveon.org/petitions/pledge-to-safeguard-the-election) which demands that election officials and office holders abide by modern electoral processes or else threaten to hold them severely accountable on this single issue in future elections if they don't.
The bulk of the pressure shouldn’t be directed at Trump himself. He will do anything to remain in power. The pressure should be directed at his ENABLERS, Republican politicians who are too timid to speak out against these flagrant abuse of democratic norms. The pressure on Republican politicians shouldn't just be coming from Trump voters - it should be coming from the entire electorate (including some Trump voters) to make them follow modern electoral procedures (which would basically lead to the popular will from within EACH STATE being expressed faithfully in the Electoral College).
We should make Republicans terrified of something much larger than Donald Trump: that we - especially Independents and moderates - will defeat them ON THIS SPECIFIC ISSUE in future elections if they don't follow contemporary electoral procedures in the current one.
I do indeed understand that this is a far from perfect solution that doesn’t address all of the issues mentioned in this article (such as gerrymandering, court packing, and ironically the Electoral College itself). But it DOES at least offer a beginning towards taking action instead of just wringing our hands and bemoaning our fate.
If you are going to “Act like this is your first coup, if you want to be sure that it’s also your last” you must ACT!