I play most with these formations:
FOR INSTANCE FC BARCELONA
-----GK------
---CB--CB----
SB---------SB
----CMF-----
AMF------CMF
--SS-----SS--
-----CF------
FOR INSTANCE BRAZIL
-----GK-----
---CB--CB---
SB--------SB
--CMF-CMF--
-AMF--------
--------SS--
---CF-CF----
This way, without a DMF, you have lots of players participating in your attacking play and you'll always find a free player to pass to when trying to find an opening. When in possesion you'll have almost every player available to receive the ball.
You should have all players' defensive arrows on high playing a zonal pressing game where every player including the strikers takes part in defending when not in possesion. Try to really play zonal pression instead of moving defenders forward to stop opponents running with the ball. Relax, your defense is still there, try to defend with your forwards and midfielders.
Especially, when not in possesion do not let the opposition lure your side backs forward chasing opposition players. Let midfielders and attackers take over pressing when they try play 1-2's on the wing so you'll have your side back covering when your opponent's winger breaks through. In fact, he will not dare break through because your side back is still there covering and will be ready to win the ball or at least block any dangerous plan.
When attacking try to vary with SS players coming through the centre and running deep on the wing (put SS attacking arrows like this: one forward, one to the centre), use short through passes straight forward when space opens up, or long high trough passes when your SB is in possesion far enough up the field to unleash a winger run. Most of all, search for combinations and openings with direct quick passing on the opposition half, you'll have enough players there. ALso put your AMF attacking arrow diagonally to the CF.
The inclusion of at least two CMF players is crucial because they can both attack and defend far up the pitch, these guys will make your game flow smooth. Best players for this position are obviously the strong allround guys like Gerrard, Vieira, Emerson, Cocu, Deco, Xavi, Nedved, Pirlo, Lampard, Cambiasso, Veron, Stankovic, Seedorf, Juninho, Riquelme, the list goes on. They do not even have to best very fast because of the fact they are CMF and will position themselves well.
Last but not least be patient. Don't use R1 too much, on or off the ball. Use R2 a lot.
Playing this way, you'll find yourselves playing dominantly, on the opposition half, creating lots of chances. In real life football you'll always hear people talk about using a '10' or playmaker, but strong dominantly attacking teams like Barca and Brazil really play with four or five 10s, coming from every possible angle.
Like we all would like to play...