The claws should be trimmed blunt before starting the procedure. See cat claw clippers . Many, many declawed cats have learned to be quite ferocious biters. Additionally, it is the rear feet that are used to do the most damage. Be calm and be careful.
Cats are hard to restrain.
You must adjust your attitude. The best option is to try to restrain as little as possible. Don't try to restrict the cat's tail. Cats use their tail to dissipate tension by swishing back and forth. Just try to work around it.