Find all the notes in the chord. If you're looking at piano music, or music with multiple instruments, the notes may be divided up among the parts. Write down all the notes in the chord; leave out non-chord tones.
Write down all the notes from the bottom up, one on top of the other. Erase or delete any repeated notes.
Analyze the intervals between each note. Most chords in tonal music are built from major or minor thirds. If all the notes are a third apart, you don't have to do anything else -- the chord is in root position. If you see seconds or fourths, it is inverted.
Rearrange the notes into thirds. The easiest way to do this is to take the bottom note and move it up an octave, so it's on the top of the chord. Keep doing this until the chords are spaced apart in thirds.
If you have moved all the notes and still do not have a root position chord, substitute enharmonic spellings for the notes. For instance, if you have a G-flat in the chord, try writing the chord out with an F-sharp, which is the same note with a different "spelling."