Bunnalina's advice was excellent! I have been using Soft Paws for about 12 years, on a total of 11 cats. I have 8 cats right now and all of them but one have no problems with them. Some seem to keep them on longer than others, and some I have to cut off because they haven't fallen off, but other than that, they are WONDERFUL!
If you have multiple cats, I highly recommend a different color for each cat. That way, if you drop one during application, you can find it a lot easier, and when they lose one you immediately know which cat needs a replacement.
If you have a cat like my cat Duck, who actively pulls them off as soon as we put them on, hold on to your cat or distract them for at least 10 minutes. A few colors have a new "grip" inside that is supposed to keep them on their claws better.
I asked Soft Paws if they had any suggestions for cats that aggressively pull them off (they have great customer service by the way), and they recommended "painting" the outside of the claw with something yucky, like chili pepper in a little water, or lemon juice, let them dry, and then apply them. Just be sure not to get any INSIDE the soft paw!!
Good luck! It may take a little practice to get them on your cat(s) but I would say it's more than worth the effort. :-)
Kitty Mama to Autumn, Duck, Louie, Luna, Peanut, Shyla, Turtle and Wee