Heads of struggling schools should be given financial incentives to allow teachers to spend time at high-performing secondaries, according to a major study released this week.
Training money should be ring-fenced so it is spent on regularly sending teachers to observe high-quality teaching in other schools, according to the Institute of Welsh Affairs (IWA).
Teachers who visit other schools are the most likely to improve and deliver better results for pupils currently underperforming at key stage 3, the IWA's Dr Stevie Upton said.
"The issue is that the best schools will do this automatically but you need to find a way to encourage all schools to do this; they need incentives," Dr Upton said.
"This should be a systematic part of a school's self-evaluation process. But it can be very difficult for schools to prioritise, especially when there are pulls on their resources from other directions.
"It can feel like a bit of an imposition and a burden, but I don't think it should be. People who actually go and see it happening on the ground are more likely to pick up on elements that will work for them. It's incredibly rewarding."
Dr Upton, who was speaking at the launch of a major study into innovation at KS3, said that good practice was a "bad traveller" in Wales.
Sharing best practice is a key element of the Assembly government's School Effectiveness Framework (SEF) and the so-called professional learning communities scheme, currently being piloted.
But some headteachers have warned that without extra funding it will not be affordable or practical to spare staff on a regular basis.
NAHT Cymru director Anna Brychan said: "I think it's a wholly welcome idea but our structures aren't such at the moment to make that easy.
"If you are going to release teachers it takes a great deal of time and commitment. You need your governors, staff body and parents on board because it means releasing people from what they are doing to do something else."
Dr Upton said that part of the money dedicated to continuing professional development should be reserved for sending staff to other schools.
The IWA's report, Making a Difference at KS3, looked at a wide range of factors affecting performance among 11-14 year olds. It follows concerns that pupil performance dips after moving to secondary schools.
The report found that continuous monitoring of individual pupils' performance was one of the most powerful tools available for improving results.
The year-long study looked at five secondary schools across Wales, chosen after a statistical analysis of their results and a study of their Estyn reports. It concluded that having detailed knowledge of each pupil allows teachers to make quick, targeted responses at the first signs of underachievement.
The report said each school sets highly ambitious targets for its pupils and constantly monitored progress, while staff are also involved in regular self-evaluation.
It also said schools must have the freedom to respond to local needs, and warned that a centralised approach to school improvement would be "ineffective".
David Reynolds, professor of educational at Southampton University, called key stage 3 the "great Welsh problem", and said more studies like this were needed.
"The problem is not that we don't know how to educate children, it's that we don't share it," he said. "This is a really important study and there's good stuff here we can build on for the future."
The Assembly government declined to comment because of next month's elections.
Original headline: Call to pay heads to let staff spend time with the very best