When making nigirizushi, it is imperative to have all the necessary ingredients to hand before you begin. If you are right handed, the sushi rice should be in a bowl on your right. Besides the toppings, you should also have wasabi to hand, and a bowl of tezu, or vinegared water for dipping hands.
Tezu is essential, because without it, the rice will stick to your hands. Ordinary water will not do either, because this will wash the sushi vinegar off the rice, and affect taste and consistency.