FIRST, after the event is over, get witness statements, find out if there are any video recordings or tape recordings. If there are, get copies of them and put them away. (Do not destroy any recordings or other evidence.)
SECOND, If you have any physical injuries, immediately seek medical attention. A nurse’s report or an x-ray can show the degree of physical injury. Not all injuries show up immediately, so take a picture of the injuries every few days. Have a copy of the daily newspaper in the photo.
THREE, California and Washington plus the Federal Government require that a TORT CLAIM FORM be filled out and filed within a short period of time from the incident. If you fail to do this you may lose your right to file certain claims. Alaska is different.
FOUR. If a criminal charge has been brought against you, check with your criminal attorney and see if bringing an Internal Affairs complaint will be a problem for your criminal defense. If the governmental agency says that there officers or employees did everything right, then you may have additional claims for negligent supervision , training or policy.
FIVE IF you have a suppression motion in your criminal case, (that is a motion to have evidence thrown out because it was obtained illegally - either through a warrantless search or excess force, intimidation, coercion, force, or lack of probable cause), the fact that you have won the suppression motion makes your civil rights case stronger.
 In California a tort claim form must be filed within 180 days of the event. If you fail to timely file you will loose your right to seek damages from the government agency or the state. The Government agency has 45 days to accept or reject your claim. For claims against the state go to http://vcgcb.ca.gov/docs/forms/claims/GCClaimForm.pdf. Local agency or governmental bodies will have a claim form in the Office of the Clerk of the body. So if you were injured in a Stockton Unified School you would go to the district offices and ask for a tort claim form.
 Rev. Code Wash. (ARCW) § 4.92.100 (2013)
§ 4.92.100. Tortious conduct of state or its agents -- Claims -- Presentment and filing -- Contents
§ 4.96.020. Tortious conduct of local governmental entities and their agents -- Claims -- Presentment and filing -- Contents
(4) No action subject to the claim filing requirements of this section shall be commenced against any local governmental entity, or against any local governmental entity's officers, employees, or volunteers, acting in such capacity, for damages arising out of tortious conduct until sixty calendar days have elapsed after the claim has first been presented to the agent of the governing body thereof. The applicable period of limitations within which an action must be commenced shall be tolled during the sixty calendar day period. For the purposes of the applicable period of limitations, an action commenced within five court days after the sixty calendar day period has elapsed is deemed to have been presented on the first day after the sixty calendar day period elapsed.
See Http://des.wa.gov/SiteCollectionDocuments/RiskManagement/allforms.pdf for the tort claim form
 A Federal Tort Claim Form must be presented within 2 years of the incident. For the Federal Government Form http://www.justice.gov/civil/docs_forms/SF-95.pdf
 Alaska Stat. § 09.50.250 The State does not allow actions against it for assault, battery, false imprisonment, false arrest, malicious prosecution, abuse of process, libel, slander, misrepresentation, deceit, or interference with contract rights or one that is based upon an act or omission of an employee of the state, exercising due care, in the execution of a statute or regulation, whether or not the statute or regulation is valid; or is an action for tort, and based upon the exercise or performance or the failure to exercise or perform a discretionary function or duty on the part of a state agency or an employee of the state, whether or not the discretion involved is abused. Civil Rights actions against the State must be brought in federal court as suits against the individual, and not the office or agency