Get free resources to learn the basics of note-reading. Borrow books and software from your school or public library that teach you how to read music. Supplement your study with free music-education sites that teach note-reading and music theory. See the Resources section for sample books and sites.
Use your books and Internet sites to study the appropriate clef and notes. These are treble clef for soprano and alto voices; treble and bass clefs for tenor voice; and bass clef for bass voice. Memorize the lines and spaces of the clef from bottom to top. Use memory aids. Remember the treble clef spaces, F, A, C, E, by the word "face." Remember the treble clef lines, E, G, B, D, F, because the letters begin the words "Every Good Boy Does Fine." Memorize the bass clef spaces bottom to top, A, C, E, G, by the saying "All Cars Eat Gas." The bass clef lines, G, B, D, F, A, spell the first letters of the sentence "Great Big Dogs Fight Animals." Learn the corresponding note on the piano for each letter name on the staff.
Practice accidentals, note-length values and time signatures. After you understand these, study the different key signatures. NotationMachine.com provides good practice in these basics.
Practice your reading with simple sheet music of your own or from a school or public library. Use a keyboard to check your pitch. Play the first note to find your starting pitch and then sing it. Then read and sing the next note aloud before checking your pitch with the piano. Continue singing each note and playing it afterward until you have finished the song. Then sing it straight through without the piano. Repeat this practice daily with different songs.
Join a singing group at school, at a place of worship or in the community. Practice your note-reading skills with the group. As you read your part along with other members of your section, you will have instant feedback about your abilities. The more you practice reading vocal music and singing, the more improvement you'll see in your note-reading.