If she taught you to play the Revolutionary Etude, she must have done something right.
You can get a little table and memorize the keys associated with sharps and flats in the key signature of your piece.
The circle of fifths comes to mind. Count on your fingers.
Thumb - C major - no sharps or flats - count to pinky finger on subsequent fingers D, E, F and
G - 1 sharp
Then Thumb - G major - count to pinky finger again A, B, C,
D - 2 sharps
Then thumb - D major... well you get the idea

Reverse the process from C major for the flats C, B, A, G,
F - 1 flat

Source - Theory 101 for the perceptually challenged. I took this course.

Cheers
allthumbs