Learn how to use your tuner. Tuners generally require you to turn it on, displaying an electronic needle that points to the key of the note you are playing. For example, plucking the thick string on a tuned guitar will cause the needle to point to an E. Some tuners will also display a solid light when you properly match the note, and it may flash when you are close but not quite there.
Press a key on your piano or pluck a string on your guitar. The thickest and thinnest strings on a guitar are both E notes, providing a good reference point. Starting with the first key on a piano, every seven keys on a piano is a C note. Ensure that your tuner is reading these notes properly before continuing.
Sing a note, attempting to match the note you just played on your instrument. Again, the tuner's needle will specify the note you are singing. If the needle does not reach the note, bend the pitch of your voice up until you are singing the note correctly. If the needle jumped past the note you are trying to hit, bend your pitch down until it matches. Remember how this vocal note sounds.
Repeat Steps 2 and 3 with other notes. For reference, the first seven keys of a piano are C, D, E, F, G, A, B, and then it repeats across the rest of the keys. On a guitar, from thickest to thinnest, the string notes are E, B, G, D, A, E. Using your tuner, you can match each note with your voice to get a feel for how each note should feel when you sing it.
Repeat Steps 2, 3 and 4 on a regular basis. If you practice every day, you will eventually begin to memorize how your voice should sound and how your throat should feel when you sing a note correctly on key. Only practice with a tuner and a tuned instrument can help you correct your vocal pitches.