If you can approach the wreck I would think the first thing, after call it in and getting emergency service moving in that direction, would be to turn off everything and kill the power. If there is no fire you want to keep it that way. Turning off the power reduces the chances of sparks and of fuel or hydraulic pumps spreading or spraying flammable liquids.

If there is no obvious fire risk don't be too quick to move occupants. Small planes often lose their wings, and most of their fuel, if they crash into trees. The fuselage may carry on for a considerable distance. Which can greatly reduce the chances of a fire threatening any survivors.

Assuming they live falling out of the sky often means traumatic damage with a high potential for spinal cord injury. If there is significant bleeding a tourniquet may be your best option. This can often be done without having to move the person so there is less chance of spinal cord injury. Staunching the worse of the bleeding and comforting them may be your best option.

If there is an imminent danger of fire you may be forced to move people. If you do try to support the neck, clothing or foam rubber from the seats might be used as an expedient cervical collar, and to keep the spine straight. Dragging a person is easier, and often less damaging, than carrying them. A blanket, tarp or other large piece of cloth can make dragging someone easier and provide some support.

If there are just a few small fires and you clearly have time and resources putting them out might be a good move. It would be good to have people survive the crash but die in a brush fire.

If your in a forest or the site is not otherwise clearly visible you might consider providing emergency services with some sort of visual clue as to where to go. In remote areas a small but smoky fire started well away from the wreck might provide this clue as would a brightly colored tarp or flag. But, as I understand it, most crashes happen near airports and responders usually have a very good feel for the immediate surrounding area so visual clues might be unnecessary.

Those are the things that come to mind but response will always be an exercise in improvisation and management. Of balancing what you can do with what should be done. Doing too much can do as much harm as doing nothing. Take a deep breath, think it through, then act.