Rule of Thumb: Reference Non-Bend Octave First
Many of our licks on the lower thee holes of the harmonica contain articulate bending, requiring attention to our intonation (how well we play in tune). We often use another instrument (most commonly the piano) or tuner to reference our pitch. A common way harmonica players do this referencing without the aid of another instrument is to play the passage in another octave. For example, the challenging lick 1 2" 3" 2" 1 can be played one octave higher as 4 5 6 5 4. So, play 4 5 6 5 4 as your reference (no bends) and then play 1 2" 3" 2" 1 right afterwards and try to match the same pitches. This doesn’t work for every lick (specifically licks with half step bends), but it works well when it is an option.