I have a pair of these that I use:
I have on occasion used a large pair of human ones but only if I really have to as they often split the nail so if using human ones, I only take the smallest amount possible off the very tips.
I use a pair simialr to these. I replace them annually because they start to get dull.
I trim all claws every month or so. Usually I get reminded it's time by someone catching me with a claw during play, or the nightly kneading gets painful. I also always trim claws the night before a vet visit.
I use butter for incentive for the cats that need it, hold the cat in my lap, upright, put a dot of butter on kitty's mouth so she has something to focus on besides what I am doing, and snip away.
Some accepted it right away, some have needed a little training, one had to be wrapped, as a kitten, but once she learned she wasn't being killed I no longer had to wrap her. She still screams through the whole thing though, just on principal. One it took years of daily paw work before I was able to trim her front claws, then another three years before she would allow the hind claws.
When released they get a final lick of butter off my finger and forget about it until next time.