Compose a song, including all basic parts: vocals, instrumental arrangements, harmonies, bridge, chorus, verses.
Practice the various parts, either alone or with other musicians, until you are satisfied with the results.
Record a draft of the song with each instrument and vocal on its own track.
Play the song back several times, paying close attention. Decide where the backmasking belongs, as well as what instrument or vocal tracks will be backmasked.
Record your soon-to-be-backmasked instrument or vocal section on its own track.
Open the not-yet-backmasked track in your recording program. Reverse the track according to the directions within the recording program.
Play back the reversed track and save it once satisfied with the results. Re-record it or choose another idea to reverse if not satisfied.
Insert the newly-reversed track into the previously recorded song where desired.
Raise or lower the volume level of all tracks until satisfied with the mix.
Compose and record a basic song as outlined above.
Choose a phrase to backmask. Play, sing or say the phrase and record this on its own.
Reverse the track through recording software as in Section 1.
Play back the reversed track repeatedly, memorizing how to play, sing or say it in its new backwards form.
Record yourself playing, singing or saying words backwards as a new track.
Insert this new track into the original song, where desired.