I use an adjustable puppy harness from Walmart, with a ribbon tied around part of it to make it fit Cyro better, since his shoulders aren't as wide as a dog's are. It's fast take on and off, with no buckles to break (at about 12 weeks old he broke out of his kitten harness chasing a cricket, plus those buckles were so tiny it was difficult to take off an excited kitten). I can adjust it as he grows, vs having to get a new jacket for him every few months. Also, I like that if he pulls or chases something, it's not right around his neck. Once he stops growing maybe I'll look into something better ... but this does work really well.
Basically, you slide it over the cat's head, put their legs through, tighten the cinch around their middle, tie the ribbon above the plastic shoulder strap adjusters (for lack of a better term), then clip the leash on
