I've been digging into music theory in the last few weeks; I finished reading Walter Piston's Harmony a couple of days ago and it gave me a great insight on a lots of things. I already know the scales and modes on the guitar for quite a while, but that book gave me a huge boost on the understanding of music, modulations and secondary dominants, all that.
To complete my "preparation" to start composing some "serious" rock-pop songs, I'd like to understand the other side of music better: the melody. From what I've understood, the melody dwells around the notes of the harmony, but that's about all I know. I've got common sense and taste, of course, but I'd like to get some formal understanding on the subject: how to build melodies, are there rules, etc. It would be great if I could find a book that enlightened me about melody as much as Piston's Harmony did about harmony.
Counterpoint seems a bit overkill. I don't want to know how to build choirs, for God's sake . Rockpop is a bit less demanding, I suppose.
Where should I be looking?