You should check the level of your antifreeze, oil, transmission fluid, power steering fluid, and brake fluid, very regularly. A good time to do so is when you fill up with gasoline/petrol. Even if your car doesn’t leak fluids at the moment, one can occur at any time and you can identify it by checking the fluid levels often. You should also check the color of some of these fluids.
Some of these have see-through plastic tanks that you can look through, and some have dipsticks. Antifreeze should be either pink, green, or yellow (Pink for newer cars with “Dex-Cool”, green for old cars with plain Ethyl-Glycol, and green or yellow for cars that have been flushed and filled with universal antifreeze…brown antifreeze should always be flushed, it either has rust or a lot of dirt in it, probably both.