Familiarize yourself with the instrument you want to convert your music notes to. If you want to make guitar tablature, for instance, you need to know where the notes are on the guitar and where they appear on the music staff so you know which notes you can select when you convert your music notes. You can purchase a simple chart at a music store that will tell you this or find one online at no charge (see Resources).
Reference the notes on the guitar neck and transfer your music notes one bar at a time, writing your note name on the string and fret location on the guitar tablature paper slowly. Double-check to make sure the tab notation is the note you are converting. For instance, if your music note is the C on the first line below the music staff, you will write that on the tablature paper with a circled number one on the fifth tab line (representing the fifth guitar string) and place it on the third fret line on the tab paper. This means the C in question is played with the first finger on the fifth string at the third fret.
Pay attention to fingering. If you are converting from a piece of music written for piano, look at the fingerboard or note locations of the instrument you're converting to. You want the tablature you create to be playable without the intended musician having to perform acrobatics to play a passage of music. This is especially important when you're doing tablature for a guitar. You may mark the notes correctly, but in such a way that no one would be able to move his fingers to play them. If you don't know something about the fingering possibilities of the instrument your creating tab for, consult with someone who actually plays the instrument.