Clean the wound. If the injury was caused by an animal or sharp object, be sure to quickly wash off debris or saliva from the affected area. Any clean water you have on you is suitable. If no drinking water is on your person, a nearby stream may also be suitable. However, it is important to do this quickly. If no other water source is present, a last ditch method of cleaning a wound is to urinate on it. This increases risk of infection later on, but can remove dirt and saliva which is worse than your urine (It is mostly water by the way). If it is not possible to clean the wound, the next most important thing to do is stop the bleeding.
Stop the bleeding. The best way to stop bleeding is to apply pressure on the wound with a porous substance. A t-shirt, sock, pants, hat, or rag will do. Be sure to tightly wrap the wound but do NOT create a tourniquet unless absolutely necessary. After the wound is dressed, apply pressure with your palm on the affected area.
Clean up the wound. You may not have alcohol or pain reliever, but you can clean the wound with soap and water, and maybe only water. Turn on the faucet (if you have one), and turn on the warm, but not hot, water. Pour some soap in your hand, and put your hand into the warm water. Rub your wound softly, and wipe off your wound with a paper towel.