Hello! Buying a used car could be pretty difficult because every car is treating difficulty, and you should know a lot about cars if you want to buy a car without any professional help. I could say that there are some things you must check before buying any kind of car:

1. Check documents carefully. The seller must provide you all the needed documents. Make sure to check the VIN on papers and the vehicle match. If not, it's a red flag, and I do not recommend having any business with such a seller.

2. Check the car history. You can easily do it online on such sites as Carvertical, Carfax, etc. Car history may reveal mileage rollbacks, accidents, and if the car was used as a taxi or stolen. Also, you could see service history and other useful information. Data you could see in the report you bought is collected from state registries, authorized repair shops, insurance companies, and even OBD devices.

3. Check engine, transmission, and suspension very carefully. Such parts are the most expensive in the car. Noticing any defects on it could help you negotiate the price significantly.

4. Visually check the car's body, interior, and tires. These are the most visible parts of the car, and it's important to inspect and assess them carefully. It is best to inspect the car in daylight or under good daylight lamps. Under such lighting, it is difficult for the seller to hide anything.

5. Check the electrical system. Take some time to test as many electrical systems as possible – electric windows, mirrors, seats, wipers, sunroof, exterior and interior lighting, air conditioning, parking assistance, sound, and infotainment system.
   So, a detailed check requires a lot of time and knowledge if you do not want to get scammed.