Based on the Marvel Previews #31, February for April 2015, I'd say you need to pre-order the following books in order to keep up with Spider-Man.
Core Titles
Amazing Spider-Man #17
Amazing Spider-Man #17, variant cover Avengers
Amazing Spider-Man #17, variant cover WTD
Amazing Spider-Man #17.1
Amazing Spider-Man #17.1, variant cover Gabrielle Dell'Otto
Marvel Universe Ultimate Spider-Man: Web Warriors #6
Miles Morales: The Ultimate Spider-Man #12
Spider-Man 2099 #11
Spider-Man And The X-Men #5
Spider-Man And The X-Men #6
True Believers: Miles Morales: The Ultimate Spider-Man #1
Guest Apps
Avengers: Millennium #1
Avengers: Millennium #2
Avengers: Millennium #3
Avengers: Millennium #4
Inhuman Special #1
Inhuman Special #1, variant cover Adam Kubert
True Believers: Civil War #1
True Believers: House Of M #1
True Believers: Infinity Gauntlet #1
True Believers: Marvel Zombies #1
True Believers: Wolverine - Old Man Logan #1
Spin-Offs
Silk #3
Silk #3, variant cover TBA
Spider-Gwen #3
Spider-Gwen #3, variant cover TBA
Reprints
Amazing Spider-Man: Edge Of Spider-Verse TPB
King-Size Kirby Slipcase HC
Secret Wars Prelude TPB
Spider-Verse HC
X-Men / Avengers: Onslaught Omnibus HC