Before you remove the cap to the brake fluid reservoir, wipe the area down thoroughly with a rag. Your braking system is sensitive, and foreign materials creeping in can clog or degrade its components. Start off clean and avoid any problems.
With the cap off, slowly add fluid until it rises to the appropriate level. Replace the cap and go about your business. In a day or two, recheck the level to be sure you don't need to add any more. So ...
- Always clean the area around the cap.
- Add brake fluid slowly.
- Recheck in a few days.
One more thing:
Never shake a bottle of brake fluid before you add it to your car. The little bubbles can cause big problems.