Find the perfect first car

Hi, I’m looking for my first own car (small car or compact class, I’m a novice driver, but already at the end of 20) and I’m still very unsure about how old and how many km it was running and what it should cost accordingly. Search for days on the portals and fluctuate in the price range 5,000-12,500 €, although I would feel more comfortable between 5,000-8,000 €. Even then I sometimes wonder if I should buy an even cheaper car after all. because it’s my first car, but fear that the repair costs are about 2,000-3,000 €. The car is supposed to last at least 4 years with average driving performance (10-15,000 km/year) (at a low purchase price) without the repairs eating up, at a higher price correspondingly longer, and is paid in cash. I don’t want to spend more than 12,500 €. What would you advise me to do? 3, 5, 7 or even 10 years old? I would like to thank you for your constructive answers if you could also afford “more” but also do not want to fry money unnecessarily? Dear premium brand (in question are BMW, Audi, MINI) and for that somewhat older or standard (in question come Ford, Opel, Peugeot, Mazda, Citroën, Suzuki, Seat) and newer date? And does it make sense to look for used LPG cars in the price range?