OK, first of all let me tell you that I play CM4, where the 2D view has made tactical play much more direct and logical. So...
I try to work with the players that are already in the squad when I go to a new team. This means that I only buy or loan players if I absolutely have to or if my scouts find a very good case of a youngster (not very often). Half the seasons I don't sign anybody at all.
So then I focus on training (....) and tactics. The 2D view helps deciding what works and what doesn't with tactics, while attribute monitoring (using the new and sophisticated pen-and-paper technology) helps with the right decisions on training.
Once I get those in order, I relax a little bit and try to strengthen the squad by signing youngsters. Who knows, maybe some day the ugly ducks will actually turn into beautiful swans (=$$$

).
By the way, this is my style of play even when I manage a top team.