Different teams play different styles, and it's therefore imperative that you change your style to suit. Think of it as rock, paper, scissors: only if you have an awesome side you might be able to cut the rock with your scissors.
The
Tactics Bible covers a lot of issues you might face including re-ranking, the weather, poor morale and poor form which can cause a team to spiral out of control if not looked after. They also cover "tweaking" and/or creating different tactic sets for different situations.
I suppose the archetypal "tweaker" approach would be Cleon, who responds to scout reports and in-game events (see the Sheffield United Project); whereas wwfan seems to go more for creating home and away tactics with different emphases on possession, closing down etc. for different styles of opponent (all the TT&F Threads).
My approach is to create a good tactic in the formation I want and learn how I can change it to different circumstances. You may lose a few to start with, but once you get into it you'll realise what changes you need to make and when. Couple that with some good transfers, and you'll fly up the league.
Not too high though - I'm a Walsall fan!