One of the best ways to practice scales is by using sequences. A sequence is a repetitive pattern in which the rhythm remains the same while the pitches are repeated higher or lower, usually within a specific scale or key. Practicing sequences will help you become more familiar with the scale you are learning, as well as enabling you to create melodies more easily instead of just running up and down the scale. Here are some sequences within the C major scale.
This sequence uses intervals of a 3rd. Try other intervals as well.