The 2004 Ford Focus ZTS is a relatively easy vehicle to maintain when compared to similar models. Checking the transmission fluid level is no problem, as the fluid dipstick is easily accessible in the engine bay. Changing the headlight bulb with reliability is easy to do, as you only have to reach behind the housing for access to the assembly. The engine coolant reservoir is easily visible in the engine bay. This will allow you to check and replenish the fluid level on a regular basis.
Some things are more problematic on the 2004 Ford Focus ZTS. The engine air filter is extremely difficult to replace. You will need to work in many different areas in order to complete this repair. You will have to peel back the wheel well lining for access to the parking light. This lining can grow tight to the vehicle and be difficult to peel back. To change the tail light bulbs, you will have to remove the tail light housing first. While not overly difficult, it does include a few odd steps that the average vehicle owner may not be able to complete.
Hans Angermeier has produced over 100,000 videos showing drivers how to fix things on their cars. He has broad expertise on basic repair procedures covering the majority of cars on the road.