Far North was welcoming two new councillors, Whangarei had three new faces and Kaipara had a fresh-start council after four years under Government-appointed commissioners.
The relative inexperience on NRC, where five out of nine councillors would be first-term, could be a concern, Mr Brown said.
"Others have only had one term, that will be hard for them. It'll be awkward to start with," he said.
"My advice is wait and listen, read absolutely everything," Mr Brown said.
"People will pick on you for their pet subject, you need a thick hide and take that. Once you're in there, you're not going to satisfy everyone. There will be things you can't do, and things that you will see need to be done, which people won't like."
Other experienced councillors retiring included WDC's Brian McLachlan, who served three terms, and Dover Samuels (NRC), whose local government experience spanned some 30 years.
Swearing in ceremonies:
Today. Public welcome.
Northland Regional Council, 1pm NRC Chambers, 36 Water St, Whangarei
Far North District Council, 10.45am FNDC chamber, Memorial Ave, Kaikohe
Kaipara District Council, 3pm KDC chambers, Dargaville
Whangarei District Council, 5.30pm, Forum North, Rust Ave, Whangarei