Your approach to practicing largely determines how you play guitar. Firstly, keeping a practice journal is a must. It is a simple means tracking what and how much you have been practicing. It is also a mirror to reflect your practice habits. It is an opportunity to be honest with yourself.
Secondly, you should be mindful of how you divide your practice time. Your practice should be divided into a few important categories. They are:
•Technique-Arpeggios, slurs, scales, miscellaneous exercises, etc...
Thirdly, HOW you practice these categories is equally important.
•Practice SLOW or slow enough to not make mistakes. If you practice mistakes, you will play mistakes. It also affords you the time to work on detail both technically and musically. You should use a metronome for slow practice and/or a tempo you can play without making any mistakes. If you make mistakes at any given tempo, you must slow down to a tempo where you do not. You can think of this as your “perfect tempo”. As you improve, you will be able to gradually increase the tempo while remaining mistake free. If you make more than three mistakes, you need to decrease the tempo.
•Practice music out of context (ie. start at the last phrase or sub phrase of a piece and practice phrase by phrase moving backwards toward the beginning). In other words, you shouldn't start at the beginning of a piece and play until you make a mistake then start over. Furthermore, you shouldn't start at the beginning of a piece a keep playing until the end even if you make mistakes. This is called "performance practice". In other words, "going for it" and letting the mistakes fall where they may (hopefully, not at all!). You need to occasionally do this, but the majority of your practice should be aim directed and purposeful.
•Implement effective strategies out of context. Some effective strategies are:
-Isolating and concentrating on the left hand only, isolating and concentrating on the right hand only, and visualizing your left and right hand fingerings "mind's eye" with your eyes closed.
-Using varied rhythms (dotted, sixteenth subdivisions, etc...)
-Slow/fast (at tempo) practice
-visualizing the music away from the guitar.
You can also couple these strategies for further benefit (ie. practicing out of context with-varied rhythms, slow/fast, or isolating each hand, etc...).
•Practice in front of a mirror. This will allow you to detect technique issues that might be missed otherwise.