Trump is the first convicted felon president. Although he won, his raw vote total was less than 50%, "the fifth smallest margin of victory in the thirty-two presidential races held since 1900."
Much of Theda Skocpol's 2017 "A guide to rebuilding the Democratic Party, from the ground up" in Vox, is still apt. Skocpol, a Harvard sociologist and political scientist urges progressives to avoid the traps of endless "election replays," squabbles over "message," failing to coordinate interests and causes, or giving procedural fixes too much importance. Instead she advocates strengthening Democratic party organizations at the national and state level, identifying groups that can replace the role formerly played by unions, organizing locally to oppose Trump, improving political intelligence, and focusing on near-term state contests. As consensus emerges for countering the Republican takeover we will update this section.
University of Sheffield's James Weinberg (UK) has a reading list on authoritarianism.
See The New Republic's Citizen's Guide to Resistance.
"So You Want to Be a Dissident?" from The New Yorker.
"A Practical Program for Resisting a Trump Second Term" from Liberal Currents
Resources for creating local ICE watch groups: defendandrecruit.org.
American Civil Liberties Union
People for the American Way's Right Wing Watch
If you're concerned about public safety consider contacting a mutual aid group in your area.