Very best thing to do upon being struck by at-fault party is to call the police and make a claim to the other party's insurance. Second best thing to do (if, for some reason, you don't wish to do the above) is to make a signed written agreement with that party, take down all drivers' license and tag info, and both drive to his bank or ATM for him to pay you immediately. Third best thing to do is to make such an agreement giving him a prompt payment deadline (within days), along with making sure you know where to find him, call him, and email him.

You could sue him in small claims court even if you didn't contact police/insurance, but (A) that is MUCH more time-consuming and inconvenient than contacting police/insurance, and (B) you may end up with a money judgment that's worth no more than the paper it's written on (after spending a few hundred in court costs)! For example, if he's married, but the wife's name is not on the car, and all of his assets are joint with his wife, there will be no assets you can collect from. If he is supporting his wife or, as a single guy, is supporting a minor child, there will be no wages you can collect from. The term we lawyers use is uncollectible.

It’s always best practices to contact the police. Especially if this accident was not your fault, it’s always best to go through the other person’s auto insurance. I’ve seen time and again how handling it “private” backfires. If you are concerned you should file a police report.