First: The only thing you should ask of the driver that hit you is for their name and their proof of insurance. Write down the other driver's name, the name of their insurance company, and their insurance policy number. If they don't have proof of insurance, things can get a little tricky...more on that later. Make a note of the license plate and the vehicle make and model. If possible, write down the VIN number too. Do not engage in casual conversation with the other driver. If you have a cell phone with a camera, take pictures of the damage to all the vehicles involved too. If you have visible injuries (like cuts, bruises, or visible swelling) take pictures of those too.
Second: Call the police. If the vehicle damage is not severe, the cars appear roadworthy, and no one appears to require immediate medical attention, the police may not be very willing to dispatch an officer, but you should call anyway. A police call log will record the fact you did, which means you took the incident seriously. If you believe that someone MAY be hurt (even slightly), tell the dispatcher and insist on an officer attending the scene. If you think an ambulance MAY be needed, tell the dispatcher. You should ALWAYS OVERESTIMATE the severity of the vehicle damage. An officer is more likely to be dispatched if property damage in excess of $1000.00 has been caused. You should ALWAYS ASSUME INJURY even when none may at first seem to have obviously occurred. Bottom line: you want an officer at the scene. A police report in your favor is very persuasive.
Third: Call your own auto insurance company. Cooperate and answer the questions you're asked as best you can, but don't volunteer information unless you are 100% certain about it. Tell them the location of the MVA and its mechanism (how it happened - the other car ran a red light, failed to yield, etc...), and who you believe was at fault. We do not recommend volunteering ANY information concerning your medical condition; it is common for people to understate the extent of their injuries, and any understatement will be used against you later. If you are pressed about your injuries, tell the insurance company representative you simply don't know how badly hurt you are, but you will follow up with them as soon as you have had an opportunity to consult with a medical professional. Get a claim number if possible, and be sure and write it down so you remember it.
Fourth: Seek medical attention. If an ambulance attends the scene, make the EMTs look you over. Ideally, ride in the ambulance to the nearest ER. If no ambulance arrives, and you are able to leave the scene in your own vehicle, drive to an ER or to an urgent care facility immediately. At the very least you should be x-rayed to make sure there are no bone breaks or fractures. Frequently, ligament and muscle injuries don't manifest immediately. You may not realize how badly hurt you are for 24-48 hours. A visit to a treatment provider immediately after an MVA is ALWAYS a good idea. We also recommend following up with your family doctor or primary care physician (PCP) within two to four days after an MVA. If you are achy or sore, insist your PCP refer you to a diagnostic imaging facility for x-rays and/or MRIs, and to a reputable physical therapist or chiropractic care provider.
Fifth: Call an attorney. An attorney will be able to advise you how to handle your claim going forward, and if necessary (if you have no major medical insurance) help you to arrange a course of medical treatment that is appropriate for the injuries you may have sustained. NEVER communicate with the other driver's insurance company (even if it's only about about property damage) UNLESS and UNTIL you have consulted an attorney. Anything you say to the liable person's insurance company WILL BE RECORDED, TWISTED, AND USED AGAINST YOU. There are NO EXCEPTIONS to this; DO NOT BE NAIVE!
Sixth: If the police do not attend the incident, after you have sought medical treatment, download a Form CR2 from TxDoT and TAKE IT TO YOUR ATTORNEY. Do not submit it without talking to your attorney first!
Seventh: If the driver responsible for the collision is uninsured you're going to be dependent on your own coverage, or potentially the Texas Crime Victims Compensation Fund. Dealing with your own insurance company in what insurers and lawyers call a "first party claim" (in contrast with a claim against another's insurance company, called a "third party claim") is as treacherous as dealing with the other driver's insurance company, only more so, because you have strict duties of cooperation with your own insurer. If you're in that situation, request a complete copy of your auto insurance policy and your declarations page (the document that details all of the dollar amounts you're insured for) from your insurer, then call a lawyer so you can be fully informed about your rights and responsibilities.
Assuming you follow this advice, you'll preserve your claim properly, and make the job of any attorney who represents you that much easier when it comes to maximizing that claim's dollar value.