An understanding of music theory is important for musicians because it enables them to read and interpret music, as well as to compose and to follow instruction from a conductor or music teacher. No one starts out instinctively knowing all the terms and concepts of music theory. Music theory thus has to be learned and practiced.

Flash Cards

Flash cards are the best way to practice music theory notes, because you need to recognize the note and its value very quickly as you read music. Make up sets of flash cards for the names of the spaces and lines of the staff and practice those every day until you know them comfortably. Then go on to flash cards that show the different kinds of notes. Finish by combining the two concepts with cards that show different notes on all of the staff spaces and lines.

Listening

A good musician is able to recognize notes and their related intervals (spaces between two notes, a physical difference in frequency) by ear ( just by listening). Play the different intervals, listening to how they sound. For example, you can start by playing a C and then a D to learn what a whole step sounds like. Then have a friend play the intervals for you, or see if you can identify the intervals using ear training software. If a friend can help you, you can make the exercise more complex by having your friend play more than one interval and then playing it back for them and identifying what intervals were in the sequence. If needed, play a reference pitch first.

Write What You Hear

Listening to a piece of music and writing down what you hear is good practice tool that forces you to apply what you are learning. If you know a song on the radio, see if you can jot the song down on staff paper. At first, you can just try to sketch an idea of where the notes go up or down. You can get more specific, such as how long each note lasts, the more you listen to the tune. To test your skills, have someone else see if they can recognize the tune from what you put on paper.

Solfege

Solfege refers to the non-pitch labels attached to scale degrees. For example, scale degree 1 is always Do. Scale degree 2 is Re, 3 is Mi, and so on. This lets you refer to intervals and notes in any key. Get a sightsinging practice book and sing the melodies provided in the book using solfege instead of pitch names. If you can recognize how notes and intervals feel in your throat and how they sound when you sing them, you will be able to reproduce those intervals even when you are without any other physical instrument and can communicate clarifications with other musicians--"Should the third note of the chord be Re or Me?"

Source:

Music Theory Practice: Drills to Practice