Here is more recent example for Gold, with resistance calculated when the gold market bottomed in 1999, so we knew in 1999 if gold ever reach 729.6 and 1024.5 there will be big resistance.
Look at what happened at the first resistance when gold hit 729.6 in 2006:
And in 2008 when it reached the second resistance of 1024.5:
Anyway, as Mike puts it, there are a lot of methods that works, but for me fibs are a good way of gauging risk and calculating logical profit objectives.