My vet cuts nails for a $5.00 fee. I just stop by without an appointment and they do it really quickly. That way i don't have to worry about buying nail clippers or cutting too deep. You should check and see if your vet offers the same service.
Here is a link to a good article about how to cut your little boys nails if you want to do it yourself.
http://www.pets.ca/articles/article-nails.htm
Hope this helps.