http://www.facebook.com/photo.php?fbid=212846415396728&set=o.184147544937339&theater  By far, the easiest technique I have found is to place the cat on his/her back.  I do this on my lap with my legs straight in front of me.  In this position, you can see well and you don't have to twist their legs.  Callie is modelling the proper form in the photo.  She was a "wild child" and still to this day, she will NEVER sit in my lap ( "Really, Honey, its been over 10 years!?!").  She would never allow me to trim her nails in a sitting position.  When you first try this technique, just gently hold them in this position without holding their feet- just let them learn to relax.  You can teach an old cat a new trick, or maybe she taught me.

I use this same technique when trimming may cat Belle's nails.  

I don't own a cat, but if I did...I would use this technique.