Ditching boot camps for troubled teens and having strong Neighbourhood Watch networks are just some of the actions one criminologist believes could better help control youth crime.

Early this year police and community leaders in Melbourne were left scrambling for solutions as pressure mounted over its handling of African street gangs.

And questions were raised over a controversial police operation in north-west Queensland where hundreds of children were stopped, questioned and photographed on the streets of Mount Isa following a spate of property crime.

So what actually works?

University of Queensland criminologist Lorraine Mazerolle said we know a lot about why young people committed crimes but less was understood about the police tactics that worked best to prevent them.

"We know that most, we think about 85 per cent, of all policing practices don't have any evidence about whether or not they work," she said.

"They have a groundswell of evidence-based policing in Victoria, but it's not easy to do these evaluations, especially in a complex political environment."

The police practices we do have evidence to support, she said, showed the entire community has a role to play in keeping delinquent behaviour in check.

Keeping graffiti and rubbish at bay can reduce youth crime. ( ABC News: Allissa Oughtred )

Neighbourhood Watch groups part of the solution

Turning a blind eye to trouble in your streets could be making youth crime issues worse, Dr Mazerolle said.

She said communities where people were willing to address bad behaviour, and weren't afraid to intervene, were less likely to see problems emerge.

"Collective efficacy is where the community is willing to intervene themselves, where they don't feel frightened," she said.

"If they see some young people walking along the street, they're willing to engage with them and not hunker, not pull away from them."

There was also evidence to show groups like Neighbourhood Watch helped empower people to learn what was happening on their streets.

Boot camps backfire

Sending young offenders into the bush to learn life lessons at a boot camp doesn't work, Dr Mazerolle said.

"We know from the evidence that punitive interventions around young people have a backfire effect — they actually increase the rate of recidivism.

"You take a whole lot of disaffected young people and put them in a room together ... you're going to increase their ties to others who have antisocial tendencies."

Dr Mazerolle says boot camps don't decrease offending, they increase it. ( ABC News: Shuba Krishnan )

Despite this, boot camps for troubled teens keep popping up.

Dr Mazerolle said they had been politically popular because the public liked solutions it could "touch and feel", but she warned governments against spending money on programs that had not been through a robust evaluation.

"If the government was really serious about evidence-based social policy they would be evaluating all of these interventions very systematically and only funding those programs that have evidence to show it works," she said.

What about liaison officers?

Police liaison officers are employed to build trust and foster understanding between police and communities they serve and protect.

They often work in areas with large migrant populations and are separate from the general duties officers most people come in contact with on a day-to-day basis.

David John, a South Sudanese man working with young African migrants in Brisbane, told ABC Radio Brisbane that liaison officers helped rebuild trust between police and his community when youths were accused of committing crimes and engaging in gang activity six years ago.

"They are the ones to be straight away between the police and whoever is there," Mr John said.

"The point is they will understand the issues."

Liaison officers are employed to help police operate in culturally diverse communities. ( 612 ABC Brisbane: Terri Begley )

Dr Mazerolle said there was no way of telling whether police liaison officers reduced youth offending in culturally diverse communities because that evaluation had not been done.

She said it was known that people who believed in the legitimacy of the police force were more likely to live within the law and self-regulate bad behaviour.

Outsourcing the development of that relationship to a single officer was where the police liaison policy fell short, she said.

"We don't want general duties officers saying engagement with the culturally and linguistically diverse community [is] up to the liaison officer.

"That's a very bad thing to happen. It's everyone's responsibility.

"General duties officers are the officers we need to engage with in a very broad-based way so they have better understandings of the very diverse communities they're dealing with."

Cleaning up reduces crime

The look of a neighbourhood could determine whether or not it was likely to experience higher rates of crime, Dr Mazerolle added.

She said people become fearful of getting involved in their community if graffiti, broken windows and other signs of disorder get out of hand.

"We've got extensive evidence to show that policing those physical signs of disorder is really important.

"It says to the community that we're in control at the really low levels of offending."

Dr Mazerolle said councils could help by creating rapid response graffiti programs and making sure damage to public places like parks and bus shelters were not left in disrepair for too long.