Get a copy of the police report a.s.a.p, names and numbers of any and all witnesses.
Take photos of all damage a.s.a.p, and get 3 repair estimates from body shops.
I have delt with several accidents that were not my fault and had to fight for
every penny from the insurance companys. A good lawyer will be worth it if
they will not pay you or their is a dispute. I handled my own paper work and
got a fair settlement.