Hi Judy ...
Hmmm, practice, practice, practice ... :grin:. Seriously, for practice, I always pick some soft stops as the articulation is much clearer as opposed to full organ. Later on, after the notes are learned, then engage the plenum.
Take it slow at first, hands first, then feet ... taking special care to learn the correct fingering & pedlaing right from the beginning. On this piece, perhaps start with the Fuge. This is the most complex part of the piece and the most challenging. Once you get the manual parts learned, then do the pedal part - alone - My teacher had me clap on the first & third beat of every measure while learning the pedal notes - that method still works for me today.
I might suggest that your personal practice time start and end with something fairly familiar that you can play well. Ending a rugged practice session on a "good note" (no pun intended) is always great positive reinforcement.
And btw, practice, practice, practice ... there is no "easy" way to learn a difiicult piece like this. Actually, it takes just as much control, if not more, to play a slow piece in absolute perfection than a really fast paced piece. For an example, check out JS Bach's
Come Sweetest Death (Virgil Fox arrangement) sometime. S-L-L-L-O-O-W-W-W-W ... one wrong note in that piece and everybody knows it without any doubts ...
.
How many ranks does the Wicks have at your church?
Ps: I moved your post into this forum as the subject matter applies better here.