Push the overton window to the left by dismantling a century of highly-effective anti-left propaganda. Educate yourself, then other people, on:

1. what “socialism”, “communism”, and “capitalism” truly mean
2. how many labor rights were won by unions (basically of them) vs kindly handed out by cApTaInS oF iNdUsTrY (basically none of them)
3. the US founders’ views on democracy, slavery, and Native Americans

developing basic literacy, media literacy, and critical thinking is also not a bad idea (I don’t mean this as a personal insult; we’re talking about a country where over half the adults are functionally illiterate, 20-30% of voters supported bombing a fictional country, and 42% of voters think the Russian government is communist)

there are many many practical steps to take as well, but it’s hard for me to see any of these leading to lasting change without fixing the (deliberately constructed) mis- and under-education in the USA.