This piece is often played too slowly. I think it "clicks" at just the right tempo, which is faster than you will hear in many recordings, and with much less pedal than one might be tempted to use. It needs to convey the feeling of the monotonous wheel spinning, spinning, spinning, only stopping at the moment where Gretchen remembers the kiss. And then, recollecting herself, she goes back to her wheel. I would recommend not listening to anyone at first and really trying to study the score objectively and to bring out everything that Schubert calls for: achieving the "sempre staccato" in the left hand, with the right articulation of the eighth notes, against the spinning right hand is a real challenge. Definitely practice this without pedal, and in performance use only very little. The spinning feeling requires a very stable tempo with very little rubato- like gooddog I also got inspiration from videos of spinning wheels, which were a common feature of life in the time the song was written. So never forget that this is what you're trying to evoke, even if one feels that one can make more "beautiful" music with the given notes.
There are so many quick crescendi from pp to forte within the space of less than three bars, and they are difficult to really go for convincingly from both singer and pianist. I think this is Gretchen's frustration- there is an apparent "Ruhe" in the music, but underneath there is a current of uneasiness and of tension. The long crescendo that start with "seines Mundes Lächeln" and up to "sein Kuss" should also be carefully controlled. I think the few bars afterwards- Gretchen's hesitation, spinning the wheel once more then stopping again, unable to forget how that kiss felt- require so much tension in the pauses, which also means almost no pedal.
In a masterclass
about this song, Graham Johnson also talks about the harmony change at "mein Busen drängt sich nach ihm hin" (my bosom urges itself towards him) and its meaning. In an earlier version of Faust, Goethe had written "mein Schoß" (my lap), but it was later changed to "mein Busen" (my bosom) to make it more socially acceptable. So this moment is Gretchen suddenly confessing to herself, in clear words, a great sexual longing for Faust. And that is when the long crescendo/ accelerando starts, which should be driven by that tension, the desire to hold him and "melt in his kisses". Johnson also points out how one must keep in mind that this intense desire was driven only by a kiss, which makes it all the more burning. Later, Gretchen will go so far as to give her mother a sleeping potion so she can admit Faust into her room. The sleeping potion turns out to be poison, and she ends up killing her own mother. She is pregnant, kneels before the statue of Mary for salvation, but is tormented with guilt and fear and haunted by visions of her own damnation.
EDIT: sorry I just realized you're playing the solo version! But I think it's important to start with the song and the text anyway:)