Familiarity is important, training will save your life.

Get an IFAK and go to a stop the bleed class https://www.stopthebleed.org/

If you’re currently versed in Firearms and are able to start a chapter, or if you are lucky enough to live in an area with a local chapter the SRA is a good organization. However they are apparently fractured and their politics may not align. https://socialistra.org/

https://www.blazingsword.org/ is better for LGBTQ+ anarchists that tend to not get along with Tankies.

A more decentralized option could be a John Brown Gun Club https://www.counterextremism.com/supremacy/john-brown-gun-club

Good basis of organized tactics. The guide below is more about organized movement than direct fire. Below will NOT help you in a firefight as it relies on a much larger trained force than you are likely to have. Good to know what the bastards study though. https://www.trngcmd.marines.mil/Portals/207/Docs/TBS/B2F2837%20Rifle%20Squad%20Tactics.pdf?ver=2015-05-27-100939-710

How to avoid getting balled up and kettled. https://theanarchistlibrary.org/library/anarch-ish-how-to-win-at-kettling-a-guide-for-non-policemen

Sabotage guide from WW2 https://www.gutenberg.org/ebooks/26184.txt.utf-8

General armed defense https://theanarchistlibrary.org/library/organizing-armed-defense-in-america

How to organize a rapid response from a very high level with further detailed resources. https://southerncoalition.org/resources/rapid-response-101/

Good general advice on organizing, also a good resource to find groups near you that are likely aligned. https://www.fiftyfifty.one/organizer-resources

Feel free to reach out for any other resources