How to trim dog hair
Hold the trimming blade firmly between your thumb and index finger (if you are too nervous or jittery it's best you don't do this). Use the rest of your fingers to grab onto the handle against the palm of your hand. Your index finger will need to go on the top part of the blade so that the edge rests on top of the middle of your thumb.
Contrary to what most people believe, this technique is actually quite a simple thing to do as long as you have the adequate technical formation. Normally this technique is done by starting at the base of the dog's neck.
Use your thumb to grab onto a lock of the dog's hair and hold it up against the blade. With a fast movement you will pull on this lock. Then grab another and do the same. Make sure to not twist your wrist while doing this is a common mistake and it will just cause you to cut the dog's hair. Instead you will need to move your arm and elbow outwards while your wrist remains rigid. To see if you are doing the right thing check to make sure the lock of hair remains in between your fingers. If you are able to see the hair follicles it means they have been pulled out, which is what you want in this case. Use your other hand to hold on to the skin on the contrary direction the process from hurting the dog. The dog will probably feel a little discomfort and might try to scratch himself. If you notice though that it is too painful for the dog, it means it is not being done the right way.