If you consider yourself an "activist" and you are not in regular communication with incarcerated people, I ask you to change that. Our side is losing every day. This is a thread with resources on how to get & stay in-touch with prisoners (political and otherwise).

First, if you have family behind bars, write to them. If you have formerly incarcerated family members, listen to them. For many black and brown people, this is the reality we need to start with. Talk to your "problematic" uncles & begin to build.

Next, it's time to look at databases of incarcerated folks who want letters. One easy and liberal/apolitical resources is https://writeaprisoner.com/ 

If you want to write to political prisoners specifically, there are many options. Here is a list of political prisoners / prisoners of war put together by the NYC Anarchist Black Cross: https://nycabc.files.wordpress.com/2020/03/nycabc_polprisonerlisting_mar2020.pdf

Here is a guide with some tips on writing to incarcerated people: https://itsgoingdown.org/bloc-party-writing-to-prisoners/

Additionally, if you'd like to write to LGBTQ+ prisoners, see Black and Pink's pen-pal program: https://www.blackandpink.org/penpal-newsletter/

Every other step related to "movement work"--direct action, mutual aid, literally anything--depends upon solid relationships, especially between incarcerated folks and those in the "free world." If you do not take the first step of communication, not much else is possible.