I vote against stickers! Keyboard shapes are so visually distinctive and physically and obviously tactile they almost memorize themselves. It’s not like guitar frets which all look the same and feel the same.
The best way is the hands-on way. Considering you already know the musical aspects of this, I’d just spell out some chords or progressions that you like and play them. You can play around with inversions if you like, that’s up to you. But really, all you need to know is that C is the note just to the left of the pair of black keys. There’s not much more to it to get started!