Use padding

Any camera bag will have enough padding to prevent the kind of damage that comes from jostling and bumping equipment together. I sometimes wrap a DSLR in a large microfibre cloth or a jumper within an ordinary backpack.

Reduce Movement

Ensure the camera can not move within it's padding, adjust a camera bag's internal dividers to make a snug fit for the equipment. When placing the bag in a vehicle, ensure the bag can't shift around, wedge it into place with other luggage or hold it down with bungie straps.

Avoid crushing

Generally this means making sure that a camera bag doesn't end up beneath other luggage and is not in a position where other items can fall on it. Mostly this boils down to carrying cameras in carry-on hand luggage when travelling by air.

Nothing else

I don't remove batteries, I don't separate lenses from cameras, I don't lock up mirrors or change switch settings. Cameras and lenses (and their mounts) are pretty strong and the only times I've had them damaged is when I've dropped them from my hand after stumbling on a rock, never in transit.