Playing scales is one of the best ways to improve musicianship. The process of playing scales strengthens and stretches your fingers, helps you develop proper form and improves your knowledge of musical theory. Properly played, scales work all of the fingers equally, which is particularly beneficial in developing pinky strength. Experience in playing scales is especially useful when learning to play more complex chords, which use a wider range of notes within the scale.
When practicing chord changes, it is productive to spend time moving back and forth between just two chords to improve muscle memory. When doing so, look for opportunities to use pivot fingers. A pivot finger remains on the same string and fret as you change chords, allowing you to anchor your hand as you move your other fingers. For example, when changing between the E chord and G chord, the middle finger can act as a pivot on the 5th string, second fret.
When you practice chord changes, do so at a pace that allows you to make the changes within a rhythm, with the notes ringing clearly. Playing slowly can build muscle memory more effectively than playing quickly . You can allow yourself to relax and work on your technique. You want your chords to sound without dead notes or a buzzing sound. As you play within your ability level, you reinforce your sense of rhythm and correct technique. Over the long term, this focus on technique over immediate results leads to faster chord changes and better musicianship.
Guitar players are notorious for avoiding music theory. While you can become a very good guitarist without having a deep knowledge of theory, an understanding of chord theory will undoubtedly improve your playing. Your brain directs your fingers as you attempt to make your chord changes. When your brain understands the structure behind its actions, it has an extra tool to improve performance. Basic chord theory can be understood within a practice session and reinforced by playing scales. By investing a small amount of time each session toward learning theory, you can significantly improve your overall learning and the speed of your chord changes.