Most police officers receive two days of public order training every year
British police risk losing the support of the public if they confront demonstrators with tactics seen as aggressive and unfair.
Her Majesty's Chief Inspector of Constabulary Denis O'Connor criticised police over inconsistent use of force.
He called on officers to respect their history of being approachable, impartial and accountable.
Police chiefs say they are changing the tactics they use - but protesters must meet them halfway.
Mr O'Connor's report into tactics in England, Wales and Northern Ireland follows his earlier criticisms of the way police handled the April 2009 G20 protests in London.
At prime minister's questions on Wednesday, Gordon Brown said the public needed to be reassured that policing was "fair".
He also said events at the G20 protests in London had led to a "great deal of anger and sadness".
Mr O'Connor's report concluded that the Metropolitan Police had not adequately planned how it would deal with the different demonstrations they knew would be taking place over the course of the two-day summit.
Separately, the Independent Police Complaints Commission has investigated the death of Ian Tomlinson, a newspaper seller, after he was pushed over by an officer during the protests.
Its file of evidence was passed to the Crown Prosecution Service (CPS) in August.
In Mr Connor's wide-ranging follow-up review of all public order tactics, the watchdog said the British model of policing was based on officers winning consent, rather than on taking orders from politicians.
Dominic Casciani, BBC home affairs correspondent
HMIC wants to see sweeping changes to public order policing - but the challenge has been a decade in the making.
In 2000, there were May Day riots in London - Churchill's statue ended up receiving a Mohican made from Parliament Square turf.
The following year the police came down hard and kettled thousands in a pen in the rain. It was a lesson in total containment and control.
Since then, have the police lost a sense of proportion? It's worth remembering there's been nothing in the UK like Genoa's 2001 G8 protests which resulted in a demonstrator being shot dead.
But technology is changing protest. Flash mobs appear by text message; autonomous groups don't talk to each other, never mind the police. Some groups like Climate Camp have no actual leader.
And all of them download their legal rights from the web - and then upload videos of officers who they think are doing wrong.
But poor policing tactics at demonstrations like the G20 had the potential to damage public confidence because officers were so clearly on display.
Mr O'Connor said there were inconsistent standards for preparing officers involved while some forces had no commanders trained in managing complex protests.
"British police risk losing the battle for the public's consent if they win public order through tactics that appear to be unfair, aggressive or inconsistent," he said.
"This harms not just the reputation of the individual officers concerned but the police service as a whole.
"The world is changing and policing needs to change with it. Public order policing needs to evolve as we move towards the London Olympics in 2012 and beyond.
"This will protect the rights of protests and the wider public as well as protecting the integrity of the British policing model."
'Clear national principles'
Mr O'Connor called for clear national principles on the use of force. Some police forces were using tactics that were far more aggressive than others, including allowing officers to hit protesters with the edge of riot shields.
And he warned police forces they could breach an individual's right to privacy by filming them or gathering other personal information without reasonable suspicion of a crime.
THE COST OF POLICING PROTEST
Drax power station 2006: £4m
Kingsnorth Climate Camp 2008: £5.3m
Tamil protests, London, 2009: £10.5m
BNP annual rally, Derbyshire 2009: £435,000
English Defence League, Birmingham, 2009: £84,000
Climate Camp, Blackheath, 2009: £2.7m
"If individuals are lawfully exercising their rights to freedom of expression and peaceful assembly, the justification for police gathering this personal information is unclear," said the report. "It is not at all obvious under what powers the police are acting in these circumstances."
The Association of Chief Police Offices said that it welcomed the report and that work had begun on a new national public order manual.
Speaking for Acpo, South Yorkshire Chief Constable Meredydd Hughes said: "This report will shape the future of national public order policing. It will drive changes in our preparation for protest and our relationships with those involved.
"Just as the service will change to meet new attitudes, protesters must understand their social responsibility.
"The service has a clear commitment to ensure peaceful protest can take place and balance the rights of everyone involved - whether taking part in protest or going about their daily business."