What I suggest you do is to write out all the bass notes of a song, then write out the melody notes beside them. Once you have all that down, take it a chord at a time until you get the whole thing written out. After you have it written out, start practicing it little by little. As you learn one part, move on to the next part. After each new part you learn, repeat the old part so u don't forget it.
As far as progressions, if you can spot the progressions in a song, then you don't have to necessarily learn the song like the CD. You can just play the song your way. You have to follow your bass notes in order to do this, that's why I tell people to follow the bass.
If you just listening to a song and picking stuff out w/out a purpose, then you are sort of wasting your time. You need to pick a specific "voice or instrument" from the song, and concentrate on learning that one part first. Once you have that part for the whole song, then go to another "voice or instrument" and follow the same process. Don't try to do it as a whole, cuz u will get confused, break it down into pieces.
One more suggestion is to listen for familiar patterns. If you can hear someting that you have heard before, or something that you have practiced already, start learning the song at that point.
