When you play, you shouldn't entirely focus on one single strategy to beat all other strategies (like the lord of the rings lol)
Instead, simply adapt, somewhat like what I've seen Jli say to response to the thread "Idealistic Army composition."
There is, of course, an idealistic Army composition, but instead of focusing on that, focus on WHAT THE OPPONENT IS DOING, most of the time, at least.
You should have a basic starting point, though, so make one thats good. Just ask if you have questions.
Scout like crazy, improve your micro if you have to. Get swordwrath presto early game, instead of turtleling(unless you're really good at it, or some other random reason), and building up giants and merics. An early attack by the opponent, if he's any good, would have beaten you before you're a good 5 minutes into the game (possibly) using that strategy.
But thats not the point. The point is to adapt to your opponent. Start with scout; if the opponent has castle archer, obviously you pull your sword or whatever you have(unless it has some chance against the archer) away. Even if the opponent sends a sword archer combo at you, you should adapt (by regretfully getting a castle archer, but if you're good, then perhaps micro around future archers, make speartons, and outwit the opponent.) Shit, I've rambled on too much. The basic point of all this is to adapt to what the opponent has, point taken. Harrass economy, and all that stuff, and blahblahblah you WON!!! GREAT JOB!!!

If you want examples to some possible builds the opponent might get, just ask, in this thread. :p
Hopefully this was some use.