Well I usually try to keep more healing items and Pokeballs than I need to, so I never have to worry about running short. Maybe it's being overly worried, but I'd rather have and not need than vice versa.
I also prefer to never save during the Elite 4 until after I beat the champion. That way if they start giving me trouble and I'm going to lose, when I restart I will be away from them and able to reevaluate my strategy.
Edit: Wait a sec- Kamikazetomato? Man it's been a long time since I've seen your username. --- OH. BANANA. "Mints make me lonely."