To guarantee your safety, check your brake fluid level regularly, roughly every 3 months. Caution, do not underestimate the importance of doing this check, which is essential for the correct functioning of your brakes, and thus, to your safety and that of your passengers.
Carrying out this process yourself is very quick and easy, and does not require enlisting the help of a professional. Firstly, you should do this check with your vehicle on a flat surface, switched off, and with the handbrake applied.
Then, open up the bonet and locate the brake fluid reservoir. It is usually found on the driver's side, made of translucent plastic, and with a screw cap on the top of it. If you are not sure of yourself, and want to avoid any mistakes, refer to your Owner's Manual and its engine schematics pages. Finally, you will need to check your brake fluid level using the dipstick (maximum line and minimum line) in the reservoir. The level should be in between these two lines. If the level comes to below the minimum line, do not fill up the brake fluid, but check the wear on the brake pads, or check that there are no leaks.