Which Formation Is Solid In Defence And Efficient In Attack?

[SongFabPersie]

I play a 4-2-3-1 with Clichy, Kjaer, Hummels, Sagna being my back four and Song and Poli sitting in front.

First season I let in 41 goals which is frankly disgusting. I still sit second though.

What can I do to make this tactic defensively sound? Please help me in any way you can - make it as in-depth as possible.

 

[Henspa]

try my tactic http://www.fm-base.co.uk/forum/f103/napoli-tactic-for-test-t69285.html#post1082265