M.R.
There is a great book, "How To Talk So Kids Will Listen and How To Listen So Kids Will Talk"
They have fabulous ideas that are very effective.
Someone mentioned to me, about words (such as NO) that you don't want them to use... have them write it on a paper (or with your help) and put it in a ziploc of water, and freeze it. Then, it's 'frozen and can't be used' ...it's a very hands-on, interactive tool that helps them understand the process of 'putting a word away not to use'
Another idea is to have him help you make a list of words he CAN use instead of NO. When he says NO, you simply state what he doesn't want, by putting it in positive words for him (this also validates his feelings) Validating feelings is important to them because it lets them know you UNDERSTAND them and LISTEN to them, but doesn't have to concede to misbehavior, you can validate yet still stand firm.
message me any time, I'd love to know how things are going.