I found several suggested read orders for the BN collections, since one complaint has been the lack of actually ordering them chronologically. 
Titans #15 Tempest returns. BN: Prelude
Green Lantern #43 Prologue
Blackest Night #0
Blackest Night #1 Power Levels 0.01% to 0.02%
Green Lantern Corps #39 Issue happens side-by-side with BN #1.
Green Lantern #44 Power Levels 0.75% to 1.20%
Blackest Night #2 Power Levels 2.63% to 3.43%
Starman #81
The Power of Shazam #48
Blackest Night: Batman #1 No power levels but the Bat Symbol is destroyed
Blackest Night: Superman #1 Power Levels 3.44% to 3.82%
Blackest Night: Titans #1 No power level's but Hawk is out of his grave
Green Lantern #45 Power Levels 45.43%
Green Lantern Corps #40 Power Levels 45.96% to 46.31%
Blackest Night: Batman #2 Power Levels 46.65% to 47.01%
The Question #37 before BN #3 because when Jason touches Ronnie in BN #3, he sees Vic Sage's empty grave
Blackest Night #3 Power Levels 50.32% to 56.59%
Adventure Comics #4
Adventure Comics #5
Justice League of America #38
Blackest Night: Superman #2
Suicide Squad #67 Power Level's 57.01%
Blackest Night: Titans #2 Power Level's 57.03%
Green Lantern #46 Power Level's 75.25%
Blackest Night: Batman #3
The Phantom Stranger #42 takes place after BN: Batman #3 Deadman's involvement.
Catwoman #83 The blackout in Gotham is mentioned.
Green Lantern Corps #41 Power Level's 85.26%
Blackest Night: Superman #3 Power Levels 93.01%
Blackest Night: Titans #3
Outsiders #23
Outsiders #24
Outsiders #25
Justice League of America #39
Justice League of America #40
Teen Titans #77
Teen Titans #78
Weird Western Tales #71
Solomon Grundy #7 after BN: Batman, Etrigan has been involved in S/B 66 & 67
Superman/Batman #66 the blackout may be a BN: Batman reference.
Superman/Batman #67
Green Lantern #47
Blackest Night #4 100%. Nekron Rises.
Blackest Night: Flash #1
Secret Six #17 Continuing from Suicide Squad #67
Secret Six #18
Doom Patrol #4
Doom Patrol #5
Booster Gold #26
Booster Gold #27
R.E.B.E.L.S. #10
R.E.B.E.L.S. #11
R.E.B.E.L.S. #12
Blackest Night: JSA #1
Blackest Night: JSA #2
Blackest Night: JSA #3
Green Lantern Corps #42 Power Levels 100%, and "100% Power Level Exceeded."
Blackest Night: Wonder Woman #1
Green Lantern #48
Blackest Night #5
Green Lantern Corps #43
Green Lantern #49
Blackest Night #6
Blackest Night: Wonder Woman #2
Blackest Night: Wonder Woman #3 Takes place in-between pages at the end of BN #6.
Blackest Night: Flash #2
Green Arrow #30- after BN #6 but before Adventure Comics #7.
Green Lantern Corps #44
Blackest Night: Flash #3 At the end everyone races toward the Spectre.
Green Lantern #50 - Parallax Rebirth. The Spectre is fought.
The Atom and Hawkman #46 the other Corps' are fighting the Spectre as seen in GL #50.
Adventure Comics #7 BL Superboy is freed. before GL #51 since BL Superboy is not seen with the rest of the BL's
Green Lantern #51 The Spectre is defeated and Parallax is taken away.
Green Lantern Corps #45 The GLC appear to transport to Earth
Blackest Night #7 Sinestro as White Lantern
Green Lantern Corps #46
Green Lantern #52
BLACKEST NIGHT #8

Titans #15 Tempest returns. BN: Prelude
Green Lantern #43 Prologue
Blackest Night #0
Blackest Night #1 Power Levels 0.01% to 0.02%
Green Lantern Corps #39 Issue happens side-by-side with BN #1.
Green Lantern #44 Power Levels 0.75% to 1.20%
Blackest Night #2 Power Levels 2.63% to 3.43%
Starman #81
The Power of Shazam #48
Blackest Night: Batman #1 No power levels but the Bat Symbol is destroyed
Blackest Night: Superman #1 Power Levels 3.44% to 3.82%
Blackest Night: Titans #1 No power level's but Hawk is out of his grave
Green Lantern #45 Power Levels 45.43%
Green Lantern Corps #40 Power Levels 45.96% to 46.31%
Blackest Night: Batman #2 Power Levels 46.65% to 47.01%
The Question #37 before BN #3 because when Jason touches Ronnie in BN #3, he sees Vic Sage's empty grave
Blackest Night #3 Power Levels 50.32% to 56.59%
Adventure Comics #4
Adventure Comics #5
Justice League of America #38
Blackest Night: Superman #2
Suicide Squad #67 Power Level's 57.01%
Blackest Night: Titans #2 Power Level's 57.03%
Green Lantern #46 Power Level's 75.25%
Blackest Night: Batman #3
The Phantom Stranger #42 takes place after BN: Batman #3 Deadman's involvement.
Catwoman #83 The blackout in Gotham is mentioned.
Green Lantern Corps #41 Power Level's 85.26%
Blackest Night: Superman #3 Power Levels 93.01%
Blackest Night: Titans #3
Outsiders #23
Outsiders #24
Outsiders #25
Justice League of America #39
Justice League of America #40
Teen Titans #77
Teen Titans #78
Weird Western Tales #71
Solomon Grundy #7 after BN: Batman, Etrigan has been involved in S/B 66 & 67
Superman/Batman #66 the blackout may be a BN: Batman reference.
Superman/Batman #67
Green Lantern #47
Blackest Night #4 100%. Nekron Rises.
Blackest Night: Flash #1
Secret Six #17 Continuing from Suicide Squad #67
Secret Six #18
Doom Patrol #4
Doom Patrol #5
Booster Gold #26
Booster Gold #27
R.E.B.E.L.S. #10
R.E.B.E.L.S. #11
R.E.B.E.L.S. #12
Blackest Night: JSA #1
Blackest Night: JSA #2
Blackest Night: JSA #3
Green Lantern Corps #42 Power Levels 100%, and "100% Power Level Exceeded."
Blackest Night: Wonder Woman #1
Green Lantern #48
Blackest Night #5
Green Lantern Corps #43
Green Lantern #49
Blackest Night #6
Blackest Night: Wonder Woman #2
Blackest Night: Wonder Woman #3 Takes place in-between pages at the end of BN #6.
Blackest Night: Flash #2
Green Arrow #30- after BN #6 but before Adventure Comics #7.
Green Lantern Corps #44
Blackest Night: Flash #3 At the end everyone races toward the Spectre.
Green Lantern #50 - Parallax Rebirth. The Spectre is fought.
The Atom and Hawkman #46 the other Corps' are fighting the Spectre as seen in GL #50.
Adventure Comics #7 BL Superboy is freed. before GL #51 since BL Superboy is not seen with the rest of the BL's
Green Lantern #51 The Spectre is defeated and Parallax is taken away.
Green Lantern Corps #45 The GLC appear to transport to Earth
Blackest Night #7 Sinestro as White Lantern
Green Lantern Corps #46
Green Lantern #52
BLACKEST NIGHT #8