In the US. As I do more irl stuff, I am becoming concerned about being arrested at a protest or whatever. I've not yet come anywhere close to this happening, but should I do some prep like this ahead of time? Are there PSL approved lawyers or something, how should I know who to call? Will I need to have the number memorized? Can I cold call them post arrest or should I form a relationship first? I don't want to get billed.
Locate an org that cares about these things. You'll know because they have their people write bail fund phone numbers on their arms at protests.
If there is no such org in your area, (1) that's fucked wtf and (2) this might be your time to shine! Getting folks to set up / use a bail fund is a good project to take on. Competent groups tend to bring lawyers as observers as well.
In terms of general lawyer advice, you won't need a lawyer until you need a lawyer. Follow this simple rule: don't talk to cops. Demand a lawyer. Get out on bail. If you had to use a public defender for that first step, don't sweat it. You can get a different lawyer after you're out on bail. Your hearing will probably be a month or more away and if you didn't tell anyone anything (especially cops) you're in as good of a position you'd have been in even with a personal lawyer there with you from the beginning.
Also, avoid getting arrested in the first place unless you're very confident and informed about the consequences and what gain you'll be making in exchange. Too many people equate getting arrested at a protest with getting cred. It's not. Cool kids get away with their crimes or reserve their arrests for things that have a direct material impact on their opponent. PMC nerds that want bragging rights get arrested for any reason that sounds cool to them.
Also follow good protest hygiene:
Use the buddy system.
Go with an org if you can.
Let someone who's not going know that you'll be there and that if you don't check in by X time that means you got arrested.
Limit your phone. Do one of these, in order of how secure they are: (1) leave your phone at home, (2) turn your phone off, (3) put your phone in airplane mode.
Use public transit and pay with cash.
Cover your face. Wear a mask like for COVID.
Wear bland clothing that will let you blend in. Blue jeans, dark T-shirt, hoody. Not black bloc, that will increase the chance that you, a random protester, will get arrested.
If things start escalating and you feel uncomfortable, leave.