The faster you ride with your board, the more useful it is to have mastered a proper braking technique. For beginners, it is recommended to press the back foot onto the asphalt, parallel (> Fig. 01) to the board, in order to reduce speed.
You can also push down the tail and use your heel (> Fig. 02) to reduce speed, but this will wear down the wood on that part of the board, which why it’s rarely done that way.
If you want to keep both feet on the board Fig. 04 while braking, you can practice the frontside (> Fig. 03) or the backside powerslide (> Fig. 04). During a powerslide, your wheels slide sideways across the asphalt. The friction reduces your speed. You need a certain speed in order to do powerslides, but once you have mastered it, it looks pretty damn cool!