Based on the Marvel Previews #102, February for April 2012, I'd say you need to pre-order the following books in order to keep up with Spider-Man.
Core Titles
Amazing Spider-Man #683
Amazing Spider-Man #683, art appreciation variant cover
Amazing Spider-Man #683, variant cover
Amazing Spider-Man #684
Amazing Spider-Man #684, variant cover
Avenging Spider-Man #6
Avenging Spider-Man #6, variant cover Adi Granov
Avenging Spider-Man #6, variant cover Marco Checchetto
Scarlet Spider #4
Ultimate Spider-Man #9
Ultimate Spider-Man Adventures #1
Guest Apps
Avengers Vs. X-Men #1
Avengers Vs. X-Men #1, blank variant cover
Avengers Vs. X-Men #1, variant cover John Romita
Avengers Vs. X-Men #1, variant cover Ryan Stegman
Avengers Vs. X-Men #2
Avengers Vs. X-Men #2, variant cover Carlo Pagulayan
Avengers Vs. X-Men #2, variant cover Nick Bradshaw
AVX: VS #1
AVX: VS #1, Spider-Man 50th Anniversary cover
AVX: VS #1, variant cover
Carnage U.S.A. #5
Daredevil #11
Daredevil #11, art appreciation variant cover
Daredevil #11, variant cover Adi Granov
FF #17
FF #17, art appreciation variant Gerald Parel
The Punisher #10
The Punisher #10, variant cover Adi Granov
Spin-Offs
Venom #15
Venom #16
Reprints
Amazing Spider-Man: Hooky
Amazing Spider-Man: Secret Origins TPB
Marvel Masterworks: The Amazing Spider-Man Vol. 14 HC
Marvel Masterworks: The Amazing Spider-Man Vol. 14 HC, variant edition
Spider-Man: Flying Blind Premiere HC
Spider-Man: Return Of The Burglar Premiere HC
Spider-Man: Return Of The Burglar Premiere HC, variant edition
Spider-Man: The Complete Ben Reilly Epic Book 4 TPB
Ultimate Spider-Man Vol 4: Death Of Spider-Man TPB