The complete shield numbering list:

Green numbers
1 – New Krypton #1
2 – Superman #681
3 – Guardian Special #1
4 – Action Comics #871
5 – Supergirl #35
6 – Superman #682
7 – Action Comics #872
8 – Supergirl #36
9 – Superman #683
10 – Action Comics #873
11 – Supergirl #37 (no number)
12 – Superman #684
13 – Action Comics #874
14 – Supergirl #38
15 – Superman #685 (no number)
16 – World of New Krypton #1
17 – Action Comics #875
18 – Supergirl #39
19 – Superman #686
20 – World of New Krypton #2
21 – Action Comics #876
22 – Supergirl #40
23 – Superman #687
24 – World of New Krypton #3
25 – Action Comics #877
26 – Supergirl #41
27 – Superman #688
28 – World of New Krypton #4
29 – Action Comics #878
30 – Supergirl #42
31 – Superman #689
32 – World of New Krypton #5
33 – Action Comics #879
34 – Supergirl #43
35 – Superman #690

Red numbers
0—Superman Secret Files 2009
1 – World of New Krypton #6
2 – Action Comics #880
3 – Supergirl #44
4 – Superman #691
5 – Jimmy Olsen #2
6 – World of New Krypton #7
7 – Action Comics #881
8 – Supergirl #45
9 – Superman #692
10 – World of New Krypton #8
11 – Action Comics #882
12 – Supergirl #46
13 – Superman #693
14 – World of New Krypton #9
15 –Action Comics #883
16 – Supergirl #47
17 – Superman #694
18 – World of New Krypton #10
19 – Action Comics #884
20 – Supergirl #48
21 – Superman #695
22 – World of New Krypton #11
23 – Action Comics #885
24 – Supergirl #49
25 – Superman #696
26 – World of New Krypton #12
27 – Action Comics #886
28 – Supergirl #50
29 – Superman #697
30 – Adventure Comics #8
31 – Last Stand of Krypton #1
32 – Action Comics #887
33 – Supergirl #51
34 – Superman #698
35 – Adventure Comics #9
36 – Last Stand of New Krypton #2
37 – Action Comics #888
38 – Adventure Comics #10
39 – Supergirl #52
40 – Superman #699
41 – Last Stand of Krypton #3
42 – Action Comics #889
43 – Adventure Comics #11

So, no big deal, because they’re so easily numbered, you can just pick good breaking points and go, right?  Wrong.  Very rarely does the storyline actually go week to week through the various series.  The World of New Krypton series actually causes a few headaches, because the majority of the issues continue directly into one another, not allowing for any good break points to jump back to the action on Earth.  So, ultimately, the shield numbers really only help to make sure that you’ve obtained all of the necessary issues.  But I have finally been able to work out a 6 volume set.

The map itself can be found here:  http://comicbinding.com/mapping/superman-2006-2011