I'm a paramedic. Notes kept in a wallet or in a pocket will not be seen. Tattoos might be seen but likely be ignored.

The only thing I look for on an unconcious patient is a med alert bracelet.

That being said, those are typically used only to suggest why the patient is currently unconcious. For example, if the bracelet states that the patient has diabetes then I will suspect​ a diabetic emergency. If they have epilepsy then I will be led towards that path.

If the bracelet says "do not revive me" then I will promptly ignore it.

You seem to be getting at what is called a DNR (do not resuscitate) order. You would need one signed by a doctor.

A bracelet isn't enough. I need a signed and legitimate DNR, as in the legal document. Without this document, you would get the full work-up.

Without a DNR handed to me, I can't get in any trouble (legal or otherwise) for beginning treatment. I have to immediately begin care. Once at a hospital, the staff will identify​ you and find your DNR in their system and efforts will end there.

Tl;dr: notes, tattoos, and braclets are a waste of time if you're trying to dodge resuscitation efforts. You need a legal document -- which likely won't be found on your person anyways.