For my experiences learning how to play a songs on the piano i love breaking them all down in to sections and simplifying them first when I don’t know the song, The when I get the hang of the simpler things I gradually ramp up the complexity of the song until until I know how to play it like the original. In my opinion that’s the most affective way to learn a lot of piano songs and techniques it’s breaking them all down in to simpler parts so you get the idea how the song is suppose to be played and then gradually getting it as close to original as you can.