Birds only have a few tablespoons of blood in their veins, and any bleeding can be life-threatening.
If you can't clip your bird's wings and nails, your vet can do it for you. To clip nails, you will need an assistant. You will also need fingernail clippers, or for large birds, a pair of dog toenail clippers, and some powdered coagulant in case of bleeding. In an emergency, cornstarch or flour will work. Nail clipping can be made much easier if you can teach your bird to lift one foot at at time.