Over the winter break, I had the opportunity to help a friend move and sort some of his sheep. This was the first time I had worked with sheep, so my 'lessons learned' will be a novice's, but may be interesting to some.
There is a certain geometry to herding sheep. Two key points: their eyes take in quite a wide angle of the world, and they will avoid people. So, herding them means getting to a point where they are between you and where you want them to go. When there are two shepherds, there seems to be a perfect position for each that forms a triangle with the desired direction of movement; after half an hour, finding that position seemed to come intuitively to me, thanks to the constant feedback and opportunities for doing it over that sheep provide.
In moving sheep, sheepdogs are great if they know what you want; sheep will naturally follow them and the shepherd doesn't have to do anything. That said, they were mostly worthless that day, distracting me by wanting to play. Their main function is to guard the sheep, apparently. Sheep donkeys are just as good at leading sheep, and (from my extremely limited experience) more reliable in taking the lead. If you have both, however, the dogs will harrass the donkey. (I think the dogs are unionized.)
Finally, if it has a working horn, a 4-door sedan can be quite effective at herding sheep across a pasture, no matter how strange it feels to do so.
