Ogoshi is the most basic hip throw and a mastery of ogoshi will allow you to more easily learn other hip throws.

Tori's power hand usually goes around the waist although it's possible to also grip the belt. Some classicalists will argue that if you grip the belt, it's no longer ogoshi but that's just academic arguments. It really doesn't matter whether you grab the belt or just the waist. Do whatever you feel comfortable doing.

The sleeve hand can grab anywhere on the sleeve or even on uke's lapel.