Before an occupation or rally or march, it is a good idea for organizers to make contact with people at local chapters of the National Lawyers Guild (NLG) and/or the American Civil Liberties Union (ACLU), if there are any in your area. The NLG will often provide legal observers for events, and can advise people on how to avoid arrest, what to do if arrested, and what to do after booked and released.
International: What is Activist Legal Support? Info and advice here http://www.activistrights.org.au/cb_pages/activist_legal_support.php
Know your rights when encountering police!
ACLU Guides available at this link:
A good discussion on police tactics at protests can be found here: http://www.activistrights.org.au/cb_pages/police_tactics.php
Policing Political Protests: http://www.activistrights.org.au/cb_pages/policing_protests.php
Why Police choose certain approaches: http://www.activistrights.org.au/cb_pages/police_tactics.php#Whycertainapproaches Which is good for analysis and assessment of the risk of police violence at Occupations at any given time.
I'm not a lawyer, but here are some basic things to avoid when carrying out a protest:
DON'T BE VIOLENT OR OVERLY AGGRESSIVE. Unless the riot police roll in, in which more organised and disciplined nonviolent responses are required, any hint of violence done by protesters is an excuse for the police to shut the protest down and arrest everyone. This includes something as inoffensive as shoving someone or throwing a cigarette at someone's shoes. Be peaceful, be firm, and don't try and start a fight. If you provoke a cop enough to start a fight, it doesn't matter if he hits you first; you're still going to jail for assaulting an officer.
Don't have any drugs on your person or in your body. Obviously caffeine and cigarettes are not that big of a deal, but if you are arrested drugs will be a major impediment to being released or not being charged. This falls under the "don't make this easy for the cops" category; if you're drunk or high or carrying drugs, you can be labeled disorderly or under the influence or many other things to excuse hauling your ass off to jail. Go sober; you may need your wits with you.
Don't break any laws which the protest hasn't planned on breaking. This includes very insignificant things like jaywalking, crossing against a light, littering, trespassing, or anything at all that could be interpreted as break a law. Some protests are based on breaking the law in some manner, this is called Civil Disobedience. This type of protest can be very effective, but you should limit the number of laws you are breaking before hand. This will reduce as sentence you and the other protesters receive if arrested, and prevent the appearance of anarchy.
Remember, once someone in a protest breaks the law, the police will try and end the protest there and then.
Humble advice: smile at cops, film them, but be careful talking to them — it is best to stay as anonymous as possible. Despite this, many movement have been successful in engaging individual police officers through deliberate fraternization (speaking with them as fellow humans). If used well fratenization can lead to widespread police/military nonco-operation (refusal to follow unjust orders or directives) Police officers are often instructed not to speak with protesters for this reason. There have already been reports of individual police officers offereing direct support, or joining the Occupations.
Know that many modern police departments compile dossiers of information on people they identify, using practices created to monitor and control young minority gang members, but likely to be used against protesters as well.
It's a good idea to have a plan in case of arrest. OccupyTucson has an Emergency Response Worksheet which allows one to designate a trusted person to activate your instructions - child care, pet care, bail, what to tell your employer, etc. FB: OccupyTucson Legal Support Working Group. http://tinyurl.com/6kx5o8o