2. Bleeding
Bleeding is, of course, one of the first and most notable signs of a compound fracture. Blood loss can be serious for many reasons. Again, it might lead to passing out if a lot of blood is lost and if this leads you to lose blood pressure (the amount of blood reaching the brain will in this case drop significantly).
Meanwhile, a loss of blood can mean a loss of iron and oxygen, and the body can only survive losing so much.
If you are forced to deal with the blood loss yourself, then you should make stopping the blood loss one of your top priorities. Do this by applying pressure to the injury using a sterile bandage. Be careful not to upset the position of the bone, but apply enough pressure to reduce the flow of blood. Try to elevate the limb at the same time.