People here mentioned the youth teams...
Here in Portugal, it all started in the eighties, when Carlos Queiroz was given the task of reformulating the youth department. And it worked. Still works today.
And it will improve in the near future, since many teams are finally having their own academies.
That's one thing that I find weird...
English teams have good academies and, yet, they don't seem to produce many quality players, like they should.