DO NOT MOVE victim if you suspect neck or spine trauma unless he is in immediate danger. Hold hands on each of head and do not let go until medical help arrives.
Upper extremity injuries: Control bleeding, if any. Splint arm in position found using available materials. Use a sling and cravats (long, skinny ties) to limit motion. Seek medical attention. Ice may slow bleeding and swelling.
Lower extremity injuries: These can cause serious internal bleeding and there can be external bleeding, too. Call for medical help.
Control bleeding, and reat for shock. Splint the limb with available materials without moving limb. Do no allow victim to bear weight on limb, as there may be a fracture.