To be fair, the only people who consider Social Democrats to be “left” are Social Democrats and the people to the right of them. Most people use “left” to refer to anti-capitalism, be it Socialism, Communism, Syndicalism, Anarchism, etc, and not to refer to Capitalism but with large safety nets.
Get organized. Join a Leftist org, find solidarity with fellow comrades, and protect each other. The Dems will not save you, it is up to the Workers to protect themselves. The Party for Socialism and Liberation and Freedom Road Socialist Organization both organize year round, every year, because the battle for progress is a constant struggle, not a single election. See if there is a chapter near you, or start one! Or, see if there’s an org you like more near you and join it, the point is that organizing is the best thing any leftist can do.
Read theory. A good primer is Blackshirts and Reds. It will help contextualize what fascism is, what causes it, and how to stop it. I can offer a good introductory reading list for Marxism if you’d like, but this is a good starting point.
Aggressively combat white supremacy, misogyny, queerphobia, and other attacks on marginalized communities. Cede no ground.
Be more industrious, and self-sufficient. Take up gardening, home repair, tinkering. It is through practice that you elevate your problem-solving capabilities. Not only will you improve your skill at one subject, but your general problem-solving muscles get strengthened as well. Theory guides practice, which sharpens theory to be reapplied to better practice.
Learn self-defense. Get armed, if practical. Be ready to protect yourself and others. The Democrats will not save us, we must save each other.
Be persistent. If you feel like a single water driplet against a mountain, think of the Grand Canyon. Oh, how our efforts pile up! With consistency, every rock, boulder, even mountain, can be drilled through with nothing but steady and persistent water droplets.