So the way it is laid out above is just the safest possible way of doing it, but there are certain simplifications that could be made that wouldn't sacrifice much safety. Lemme go over it:

1. red on dead
2. red on donor

The reasons you don't simplify this to "connect the positives" are pretty minor, but worth considering. If you connect the dead one's positive first, that means that the positive lead that you're holding that isn't attached has a lower voltage relative to that battery's ground than if you had attached the donor first. Thus if you accidentally short the unconnected red lead, it's a lower voltage difference if you're connected to the dead one than the donor.

Additionally, you'd be shorting a dead battery and not the battery of a car that still functions, and thus if you mess up and destroy the battery, there's still at least one functioning car. (This is probably the more major reason)

1. black on donor

2. black on bare metal

The reason you don't simplify this as "connect the negatives" is that when you charge a battery, it can release flammable gas (hydrogen, I think?). When you pull off any of the leads after you're done charging, it is very likely to create a spark as you do. By connecting the black to bare metal, it is far from the battery, and thus when you pull off that lead first, the spark will occur nowhere near a battery that might have flammable gas.

1. start donor

2. start dead

So this one is probably a little over-cautious, but still technically a little safer. I believe this has to do with potentially damaging the electronics in the donor car by causing voltage spikes if the donor car is just left on as you connect and disconnect them. But definitely start the donor before the dead if it's not already running or you could risk having two dead batteries.