In addition to The great advice in JC’s post right above, which you should go woodshed right now, take the heat of memorizing off of yourself. Your list of Cat Stevens songs...why do you love each one of them? Which bits give you the smiles? There are theory and production reasons behind those bits. Learn the why along with the how. Just for those songs to start. As you learn that your brain will eventually make its way from the slow process of analysis, to the faster process of recognition. Start with Peace Train. One of the things to study about that song is what the melody does against the chords. It’s almost a sonic version of the visual barber shop pole effect.