Introducing a new cat: Cat-Friendly Homes suggests isolating a new kitty at the beginning. Often the kittens' HUG delivers can be introduced to your cat in a playpen, that HUG will loan you. So, unless that isn’t working, there is no need to isolate and wait before introducing the kitties.
This website has excellent suggestions on what to do if a conflict arises between your cats.
Kitten Lady provides educational media, training resources, and instructional workshops that help individuals and animal shelters learn how to save the lives of kittens—in a fun and engaging format.
It may be necessary to foster a feral cat for longer than the normal length of a TNR project. The cat may be injured or ill, nursing, or need to be held until the relocation is arranged. Neighborhood Cats provides step-by-step instructions on how to create a safe, long-term housing setup for ferals.
Mike Phillips of the Urban Cat League and the NYC Feral Cat Initiative teach how to tame feral kittens and prepare them for adoption in these instructional videos.
Urban Cat League provides videos and tips to learn how to socialize and tame ferals.