So, I wrote a canon before I was even thinking about writing a fugue and I found it to be trivially easy. But then again, I did take the Pachelbel approach, decide on a bass line and then make everything harmonically fit. Harmonies changed as I made more variations on the melody but I still kept all my dissonances either short passing and neighbor tones(so all my leaps were between consonances) or as a seventh resolving the way it should. That and my canon was at the unison.
A more Bachian approach would be to start with just the melody and then as I add voices, the bass line just appears from what seems like nowhere. No ground bass like in Pachelbel. Closer to a fugue in its nature except there is no countersubject or any other kind of contrasting melodic material between voices that isn't simply due to a delay in the appearance of a particular group of notes which is intrinsic to a canon.
My attempts at writing a 4 voice fugue have been futile. I was always thinking:
Well I have to keep the interval between the tenor and the bass at most a 9th and same for the alto and soprano since the largest interval I can play on the piano with 1 hand is a 9th. Interval between tenor and alto though doesn't matter because the tenor is in the left hand and the alto is in the right hand.
This has, every single time for me, lead to an instance of parallel octaves because I'm like:
Okay, I have reached an octave, now what? Going down to a 7th won't work because that will lead me back to the same octave. Going to a 9th also won't work unless it is between the tenor and the alto because I can't play a 10th interval with a single hand so if the 9th is between the tenor and the bass or between the alto and the soprano, my only choices are either to go back down to an octave or to leap. Going back to an octave seems like the better option because I conserve leaps, but it just delays the resolution of the octave. Contrary motion to a 6th might work, but what if that doesn't fit with the harmony? Only other solution I can think of that doesn't break the parallel octaves rule is a leap in 1 or both voices involved in the octave. And in general I want to use as few leaps as possible outside of maybe a subject entry, and if I have to use a leap, I would prefer a third over a sixth.
And sometimes I don't see any solution other than going to another octave and that is when I break one of the most important rules in counterpoint if I want multiple independent voices and not just octaves of registration, that being:
No parallel perfect consonances
And this makes my attempts futile because I am doing everything I can to prevent parallel octaves and it happens anyway. So I was thinking that maybe I'm just not ready for 4 voices yet. If parallel octaves are my main contrapuntal weakness, then I should probably start from 2 or 3 voices, where I am less likely to run into the situation of parallel octaves because there are fewer voice combinations that could have an octave and thus fewer resolutions for any octave that I would have to worry about. That and the octave is not a necessity with 2 or 3 voices unlike how it is with 4 voices. I can simply avoid octaves if everything else fails. So I was thinking of doing this:
2 part canon, try to avoid the octave if I can
2 part invention, again trying to avoid the octave if I can
3 part canon, allow a few octaves so that I can make sure to resolve them properly without any bad parallels
3 voice fugue, again allowing for a few octaves
Keep doing 2 and 3 voices, allowing more and more octaves as I get better at resolving octaves
Once I can have a lot of octaves without any parallel octaves in 2 and 3 voices, then do a 4 voice canon and see if I can avoid parallel octaves when the octave becomes necessary
If I get parallel octaves with 4 voices, go back down to 3 voices
Once I can get no parallel octaves with a 4 voice canon where the octave is a necessary interval, then do a 4 voice fugue
After this I should be able to do 5 voice and 6 voice counterpoint easily while still avoiding parallel octaves
Will this help me avoid parallel octaves in my fugues no matter how many voices or how complex the fugue gets, starting with 2 and 3 voices and gradually allowing more octaves as I get better at resolving octaves before moving on to 4 voices or more?
EDIT: I added a notation example of one of my fugue drafts. It has parallel octaves but it also has octaves that go to another interval. The parallel octaves are in red.