How to respond to someone rude?

Some are just inherently negative people who are rude for no reason. Sometimes they say it in an indirect way, I am not soft or slow but how to get the cues well and become witty/clever and reply at the instant. I know its not a 1 night process but how and where to start? Sometimes I get emotional from inside if I have verbal fight, any way to slowly change that and not let it get it to my emotions. Not responding or ignoring is not an option as I will keep remembering it and think about it.