Learn each of the intervals by using the chromatic scale. There are 12 intervals that you must know. The minor and major second, minor and major third, perfect fourth and fifth, major and minor sixth, major and minor seventh, octave and tritone. The Musical Intervals Tutor will help you to recognize each interval by sight and aurally.
Practice playing each interval on the piano. Start on the lowest C and play minor seconds from the bottom to the highest pitch. After playing all the intervals starting on C, start on C#, and then D. If you use these three pitches, you will play every interval possibility on the piano.
Continue the process from Step 2 by playing a major second. Do this for each of the 12 intervals. For instance, when playing a major second, you will start on C and then move to D, E, F#, G# and continue up the scale playing major seconds.
Create 12 flash cards for each of the 18 most common notes in the chromatic scale: C, C#, Db, D, D#, Eb, E, F, F#, Gb, G, G#, Ab, A, A#, Bb, B and C. Pick an interval that you will play ahead of time and select a random card after shuffling. Play the interval above the note selected as quickly as possible.