What is the best way to practice guitar scales?
Start on the first note of the scale and play up four notes. Then start on the second note and play up four notes again. Continue this pattern up the scale and then back down. This is a good way of developing a "way out" of a scale because you are playing four notes of a scale and then skipping.
Are Scales good to learn on guitar?
Practicing scales enhances finger technique and because the hands are synchronized, better rhythmic soloing. This increases the knowledge and ability to play various melodies over the right chords at the right time. Learning and practicing scales is invaluable and will lead you to complete mastery of the guitar faster.