One of the most important parts of developing as a musician is listening to a lot of music. It's especially critical to listen to other harmonica players, but any music you listen to has valuable lessons to teach you.

When listening to other harmonica players, check out their tone on the instrument (which is a function of their playing and their amplification if they're playing through a microphone — more on this later), the way they phrase their musical ideas, and the way they interact with their band. When you hear things you like, try to emulate them. When you hear things you don't like, avoid them in your own playing.

A narrower form of listening that's valuable is to listen for riffs you can “steal” and use yourself. “Steal” is in quotes because the borrowing of riffs is a long-standing and honorable tradition in music. The famous jazz guitarist Barney Kessel once said, “Borrow from one guy — that's plagiarism. Borrow from two or more — that's research.” In fact, all musicians are the sum of their musical influences, and what makes each musician unique is that everybody's combination of influences is different.

When you find a riff you like and want to learn, listen to it over and over again until you know how it goes. Then slow the tempo way down and learn the riff at a tempo at which you can play it, speeding it up gradually once you know it.

Playing along with recordings is another excellent form of practice. It gives you the opportunity to play along with a band — often a great band — that affords you a very different and more lively experience than practicing alone with a metronome. There are even recordings that purposely leave out the harmonica part so you can play it yourself. The best-known manufacturer of such recordings is Music Minus One, but there are other series as well.

Note here that the music you listen to will be in a variety of keys, so you'll require a variety of harmonicas in keys other than C to play along. A good set of other harmonicas to start with would be an A harp, a D harp, an E harp, and an F harp, which will allow you to play cross harp for most common blues songs in the keys of E, A, B, and C, besides the key of G that you can play on your C harmonica.

If you already know what kind of music you want to play, listen to and practice in that style as much as possible after learning the fundamentals of playing harmonica.

Another tremendously valuable form of listening is listening to yourself play. This allows you to get outside your own head and body and hear what you sound like from the outside, from a listener's point of view. It's a great idea to have a tape recorder or a digital recorder sitting next to you when you practice so you can record yourself and listen back later to evaluate yourself.