"What's the best way to prepare for watching a big cup match?"
Mate, get yourself a industrial-sized vat of energy drink, mainline it through a funnel, then practice your screaming by yelling match commentary at pigeons in the park for three hours straight. By kickoff you'll be so wired the actual game will seem slow-motion, and the pigeons will've filed a noise complaint that'll get you banned from the stadium anyway, so really you've won before it started.