I have always found that the reward system works best, be it a surprise outing for being so good or a touch on the head with some nice words ! Kids cant get enough praise.

Pocket money with a trip once a week to spend it works well.

Ignoring (this is hard) some bad things and only stepping in when its a danger to the child or others.

It works wonders with five of my six children (one has mental health issues) eldest 20 younges 4.

Our four year old is 'persistant' lol so its harder work with him however we are getting there.

If you have to punish then the chair (if hes seven then seven minutes) or a corner with no talking. Or work in the house for an hour or half an hour whatever suits you. (hoovering polishing cleaning the fridge etc)

I think the main message is to be consistant. Pick your battles so you know you will win (he will learn to accept you winning) and keep at it.

As for other people..... Ignore them !