Based on the Marvel Previews #20, March for May 2014, I'd say you need to pre-order the following books in order to keep up with Spider-Man.
Core Titles
Amazing Spider-Man #1.1
Amazing Spider-Man #1.1, variant cover John Romita Jr.
Amazing Spider-Man #1.1, variant sketch cover Alex Ross
Amazing Spider-Man #2
Amazing Spider-Man #2, variant cover Mike Deodato
Giant-Size Spider-Man #1
Marvel Universe Ultimate Spider-Man #26
Miles Morales: The Ultimate Spider-Man #1
Miles Morales: The Ultimate Spider-Man #1, variant cover Brandon Peterson
Miles Morales: The Ultimate Spider-Man #1, variant cover Fiona Staples
Superior Foes Of Spider-Man #13
Guest Apps
All-New Ultimates #2
All-New Ultimates #2, variant cover Ron Wimberly
Amazing X-Men #7
Deadpool Annual #2
Original Sin #1
Original Sin #1, blank variant cover
Original Sin #1, interlocking battle variant cover Art Adams
Original Sin #1, teaser variant cover
Original Sin #1, variant cover Ed McGuinness
Original Sin #1, variant cover Gabriele Dell'Otto
Original Sin #1, variant cover Skottie Young
Original Sin #2
Original Sin #2, interlocking battle variant cover Art Adams
Original Sin #2, teaser variant cover
Original Sin #2, variant cover Gabriele Dell'Otto
Spin-Offs
Deadpool Vs. Carnage #3
Reprints
Jeph Loeb & Time Sale: Yellow, Blue And Gray HC
Marvel Universe Ultimate Spider-Man Vol. 6 Digest TPB
Superior Spider-Man Vol. 6: Goblin Nation TPB