Since i'm self taught, I don't really know how to go about this. Do i memorize the notes on the fretboard, the different chords in a scale, etc?
First of all, I would highly recommend you to get a teacher. I cannot stress this enough. Being self-taught is not a badge of honor, but an obstacle in your way to become a great guitarist.
Theory practice consists of the following things:
- Scales: For a start, you should learn all positions of the Major natural scale and know where the root is located in each position. This will allow you to pinpoint notes a lot faster and improvise a lot better. The reason that the Major natural scale is the most important to learn is because it contains more scales in it (Modes - Same notes but with a different root), the Minor natural being one of them.
- Scale degrees: Diatonic scales have 7 notes. Each note is a degree on the scale. Lets take for example the C major scale: It consists of C (I), D (II), E (III), F (IV), G (V), A (VI) and B (VII). The degrees of the scale tell us what chords are a part of the scale:
The 1st degree of a major scale is a major chord, the 2nd is a minor, the 3rd is a minor, the 4th is a major, the 5th is a major, the 6th is a minor and the 7th is a diminished.
- Chord notes: For every new chord you learn, you should check, write and memorize what notes the chord consists of. This will help you when you write your own music, improvise with a friend and with arpeggios.
- Reading sheet music: Every musician should be able to read sheet music. It allows you to communicate with a wider range of musicians, understand theory better (for example, seeing the intervals with scales) and makes it a lot easier for you to work in a band.
- Ear training: Not really theory practice but it is very important for you to be able to recognize a chord or an interval by ear. You should start your ear training with interval hearing (how many tones are two notes apart), and always tune your guitar before playing so you would be able to tell what notes sound in-tune.