I've found that 3N-1(DMC)-3N-2W(AML/AMR)-1 wins for me everytime against 4-3-3 , even against +5 quality points stronger than me.
Just this week I've beaten the top of the league team 3-0 using it.
As 4-3-3 is essentially an attacking formation....i use normal mentality ,long passing down both flanks, normal tackling ,with pressing own half and counter attack on.........no offside.By the time your opponent has killed himself by trying to bypass your 7 defenders and midfielders with his 6 attackers and midfielders you should notice as the match progresses that you get more chances leading to goals. I always like my aml or amr as a shadow striker to back up my lone striker up front....
Anyway it works for me.......