After being involved in any motor vehicle accident, you will want to receive medical care quickly. Make sure to have your condition evaluated by a professional, even when you do not think that you were hurt. If you go to a hospital later, the insurance company will inevitably use the delay in treatment to argue your injuries must not have been very severe.
Collect whatever evidence you can at the scene of the crash. In most cases, the easiest thing to do is use your cell phone to take pictures of everything involved in the accidents. Find out if any people saw the crash and ask them for their contact information. They may be needed later as witnesses. Make sure an attorney is the first person you talk to about your accident and refuse any insurance company offers to provide recorded statements until you have legal representation.