Re: melodic improvisation
Your best bet is to learn solfege. If you can develop your ear to understand the FUNCTION of the notes, you will be far ahead of the game. Be prepared though, as it takes time. Dr. Thom Mason from USC wrote an excellent text which applies solfege to improvisation entitled "The Art of Hearing." You might want to pick it up. Also, you might want to enroll in a musicianship class at a local community college to brush up on solfege.