What are ways to improve running speed?

There are several training methods to increase your race speed, they all play with tempo in different forms.
Interval training is one way to increase running speed. In this form of training, you alternate between slow and fast tempos within a training session. You run through several repetitions alternating between fast running pace and trotting pauses. Depending on the target distance and speed, this training unit can be designed differently. A marathon runner goes through a different interval training as a 800 meter runner.
Another way to train and increase the running speed are tempo runs. Here you run at a higher pace than the actual target pace. The intensity of the load is correspondingly high, the duration of the load and the distance is therefore shorter.
Overall, however, it is important to remember that base training is just as important for increasing race speed as fast tempo sessions. With long runs, the appropriate foundations are laid in order to build them up with the previously mentioned speed units.