Disregard critics and accusers.
Activists should be aware that some will try to discourage you from pursuing your cause. Don't allow them to distract you from what you're doing. Just keep on keeping on.
Disinformation
I like to distinguish disinformation from propaganda. Whatever dictionaries may say about it, as far as I'm concerned, propaganda is showing the good and hiding the bad. Disinformation is false "facts", or presenting lies as facts. It's also polluting an issue with outrageous "facts" in an attempt to discredit opponents.
I don't mean to say that pranksters don't exist. There are plenty of people out there with nothing better to do. But they only add to the problem. They are not the main source of the crap out there in cyberland.
Don't automatically dismiss conspiracy newsletters or tabloids. When people without proof get desperate enough, this is where they'll run to.
"Fishing Nets"
Now here's a tricky one. You're only likely to come across these when you're dealing with very sensitive, if not explosive issues. I don't know if there's another name for it, but what I call the "fishing net" is a bogus organization setup for the express purpose of exhausting activist time, effort, and perhaps financial resources in an attempt to nullify opposition.
The whole shit basically comes down to this:
Never blindly trust anyone.
Always think for yourself.
Do your homework.
And finally, although there may be strength in numbers, if you really believe in a cause, don't limit your activities to the group effort. YOU may be ok, but there's no way to vouch for anyone else.