The key to playing this piece well lies in considering and performing the left and right voices independently. Although dynamic markings are written, they should not be taken at face value. The dynamic markings written here should be considered in terms of the entire section, rather than just a specific measure or spot. For example, the forte written in the opening measure should be understood as representing the entire section, such as over four or eight measures, rather than making the initial F extremely loud.

It is uncertain whether these dynamic markings were written in that era or added by an editor. In any case, even if we assume they were written by the composer, performing on modern instruments differs from performances of that era, so there is no need to be overly concerned about them.

With this in mind, it would be acceptable to start the opening at p and transition to forte from the A minor section at measure 12. The author would perform it that way.

Let's assume the subject of this fugue is four measures long. For a clear example, consider the opening four measures as the subject. The subject ascends by a second in each measure, then descends in the fourth measure, doesn't it? Therefore, if you start at p, gradually increase the volume towards the third measure, and then return to p in the fourth measure. The right hand in measures 5-8 appears as the subject in C major, doesn't it?

For the learner, which is louder: the initial F major subject or the C major subject? Let's discuss this with your teacher. In measure 11, the subject begins in A minor, but this initial A can also be considered the resolution of measure 10, so it is preferable to play it softer than the G# in the previous measure. Similarly, the left hand descends from E in measure 10 to A in measure 11, reaching a cadence, so this A should also be soft.

The A minor theme might be the most tense so far, so playing it forte would be acceptable, but since measure 13 is the peak point for the right-hand voice and measure 15 is the peak point for the other voice, treat each voice individually and be careful not to have the left and right hands at the same volume.

In measure 17, it returns to F major, doesn't it? This time, it's "mirroring," meaning if you read the score upside down, it matches measures 1-4, doesn't it? This time, it might be interesting to have the opposite dynamic to measures 1-4, perhaps starting loudest at measure 17, gradually decreasing to measure 19, and then crescendoing again at measure 20.