Learned from, and still learning, from my grandfather. 50+ years working with cattle, he knows his stuff pretty well. Usually we use a thick stick, maybe about 4 foot, couple inches wide or we use about a 5ft pipe, bout half an inch across. Sometimes he uses a whip, but never cracks it. He usually taps them with it. Sometimes we use a hotshot on the bull calves that are being stubborn, but we've probably used the one we have now about a maximum of 20 times and we've had it 5+ years. Sometimes he grunts a little at them, but never really yells.
Usually I don't use anything, but if I'm working with cows that are a little bit more spookier, I use the pipe I mentioned. Sometimes I use a small PCP pipe about 3 1/2- 4 foot long. But now since we've almost sold out we usually don't have to use anything, maybe the whip, but never really cracking it. Most of the time I raise my hands, wave a little and sometimes snap my fingers to get their attention, or I cluck at them like I do my horses, or smooch at them like a dog to get the attention of the heifers and calves. Usually the older cows require a bit of waving.
I also learned what NOT to do from the local salebarn. They hotshot them until they have their tongues out and foaming at the mouth and bellering. There's one guy who operates the gates who I usually want to just knock upside the head with the paddle he uses. He uses one of the paddles with the BB's in the end and just whacks the cows in the face as hard as he can manage and I swear he closes the gate too soon so it gets the cows hindquarters or their heads. He's an older man, but he's just so ignorant with what he does. Today he repeatedly hotshotted a cow until she reared to jump over the railing, and I just shook my head. It's really angering how much they hotshot them in this heat, 100+. Just awful.