My personal approach.

Firstly,
Focus on transition from BPO (Ball possession Opp) to BP (Ball possession) in our defensive half.

The key difference between Barcelona and everyone else in my opinion is there speed of transition is quicker than anyone else.

So if we can transition from BPO to BP quicker than they can transition into pressing than that is one step into stopping there dominance.

The reason why I have chosen this area is because in my opinion teams should always be able to transition to BP quicker than the opposition can transition into BPO in the defensive half for a couple of reasons.
- Numerical advantage therefore if all players move at the same pace we should be able to find our spare player.
- Ball moves faster than players

Secondly,
Are Barcelona a good BPO team in there defensive half?
In my opinion this is an area that teams rarely exploit.

So instead of counter attacking all the time like every team seems to do, we will keep the ball (this links back to point 1). And put Barcelona in a position where they feel uncomfortable... without the ball.
Patiently building up also means if we don't score well then in any case we will spend less time defending.


Thirdly,
The hardest question of all.
Whether to press Barcelona high or drop deep?

In short if you press them high there is space in behind and pressing for an entire game is physically demanding.

If you drop deep to half way then there is a fear you will be chasing shadows for a whole game and Barcelona are the best in the world at breaking down deep defenses.
However dropping deep restricts the space in behind and you can control the gaps in between the midfield and defense.

There is no ideal way to defend Barcelona when they have the ball but personally I would press certain players in certain situations.
E.g. There is no point in pressing Xavi or Iniesta high up the park but Busquets is definitely someone who can get caught on the ball in my opinion.

To press Barcelona you would need very quick back four and your front 3 would need to work extremely hard you can't have a lazy number 9 every player needs to be part of the press or they will find that one player they need to get passed the press.

Obviously this is all easier said than done but all for a bit of a discussion.

Looking forward to hearing some responses.