First thing, take care of yourself and others. Find out if anyone is hurt if anyone requires emergency assistance, 911

If you're travelling with a camera or camera phone, it's a good idea to take pictures at the scene. Get shots of the vehicles involved, damages and license plates. This kind of documentation may help later with your claims.

Share insurance information with the other drivers, as well as names, address and phone numbers. Write down the other vehicle's make, model and license number. 

Call local law enforcement to the scene or go to the nearest station to complete a report.  Try to obtain a copy or ask the officer for the report number.

Contact your insurance company as soon as possible to report your accident and any damages.

If you are considering hiring a lawyer, do not give a statement under oath.  If you give a statement, make it conditional on the insurer providing you with a copy of your statement.