Clipping the ears of your pitbull's ears require a lot of preparation. It can only be done if your pet is at the right age to go through it. You will easily find a lot of people who are against the idea of ear clipping as it inflicts a lot of pain. Mutilation is often used as a word to describe ear clipping.
First thing is first, ask yourself why would you want to clip the ears of your pitbull? Has it got to do with the fact that you are putting him on a show? If so, at least you have a reason despite it is still a cruel thing to do. If it is only for the purpose to make your pitbull look cute, then please forget about it. It puts your pet at risk of getting an ear infection.
How about getting them a toy? Buy them a nice puppy shirt to let them look good. How about spending some money on a nice dog collar? I believe they will just adore and love you much more than ever!
Most dog will love to have their ears rubbed and clipping your pitbull's ear will take away that joy from them. Subjecting them through the pain of having their ears clipped and wounded is enough reason for them not desiring anyone to touch their ears ever again! Why would you want to do something that causes a life long negative impact in the relationship between you and your pet? Truth is, dogs suffer an imaginary pain from the clipping even up to the end of their life span.
Let me ask you a question, would you be afraid of the dark after you have actually seen a ghost? Of course you would. Some fears remain with us for life! Having such traumatic experiences requires psychological therapy and even that itself is not a guaranteed cure. Try imagine being a dog and asking for psychological help. That is not going to work. It is akin to praying for a miracle.
If for some reason you are forced to clip the ears of your pitbull, then for goodness sake, wait for it to grow to the right age first! There is an age period where the pitbull's ears are fine for clipping and you can't do it too soon before or too late after it. If you are not an experienced vet, then never think about a DIY in this case as you do not know what you are doing. It is going to be a mess if you do so and most likely you may ending up causing the death of your pet. Why not go see a vet and ask for their professional opinion on the matter of clipping your pitbull's ears. Ask your vet, how old should a pitbull be to have its ears clipped? Having the age right is half the battle won in this case.