I have pet clippers, but I'm really scared i'll hurt the dog or something if I do it myself. His nails are gigantic... 
Get the vet to show you next time, how far back you should clip him. I would be too afraid to clip them myself on the cats. I do have some cat furniture and they have a scratching post to scratch on, plus they go outside and climb trees but getting them clipped is good.
I will stick to doing my own nails I think.