First off, start clipping dogs nails when they are young, get them accustom to the fact that you will be cutting their nails.  This will save a lot of trouble later on, because us dogs need to trust you humans from an early age.  If you didn't make us feel comfortable with you doing this from early on, you have to make the experience comfortable for us, feed us a snack or some treats as you cut the nails, just so we know that you are rewarding us for letting you do this nail trimming to us.  Another idea is have more then one person help you, yes, just picture this as an enjoyable pedicure for us, one of you humans feeding us a little food while the other does the nail clipping.

      Now, an important thing that you humans might not realize.  There is a vein running through our nail.  If you look carefully you should be able to see the vein running through the nail.  My sister Jackie has black nails and it makes it much harder to see this vein.  Be very careful not to cut the nails too short.  However, accidents do happen, after all, you're only humans.  If an accident should occur, have some styptic powder handy, you can get this at any pet store.  This will help stop the bleeding if you cut the nails too short.  Dip your finger in the powder and then on to the nail that you cut too short.   If you've cut your dogs nails and you don't have styptic powder handy, and you cut the little vein in the toenail then you can use flour or cornstarch to help the clotting process.

       A little bit of care and you shouldn't have a problem cutting our nails...just make sure you don't cut the nail too short, look for the little vein running through the nail and don't cut it, but if you do cut it, you must use styptic powder, cornstarch or flour to help the nail clot and to stop the bleeding.  It isn't a wise idea to let us bleed from the toenails, we need help to stop the bleeding, so definitely use the powder suggestion.