Published by Consumer Focus, the report says engaging with local communities and local authorities can help ensure services remain accessible to rural residents despite changes.
The document - unveiled ahead of a nationwide restructuring of the post office network in 2012 - focuses on the way Devon County Council dealt with the loss of post offices during the closure programme in 2007.
Although the 2012 programme won't involve closures, Andy Burrows of Consumer Focus said customers would inevitably be at the sharp end of any changes to their local post office service.
"Now is the time to look ahead and agree what can be done to ensure this programme of change is implemented as smoothly as possible for consumers.
"The starting point must be a planned approach which gives local people and authorities the chance to anticipate and tackle problems that may arise."
Devon County Council's response to the closure programme kept a post office service alive in many areas.
The council provided funds and co-ordinated advice from other organisations to protect post offices and give community shops the best chance of thriving. It was particularly successful at getting the local community involved to ensure the long-term future of these outlets.
Mr Burrows said: "The single most important lesson is that the better the impacts on local communities are understood, and the more clearly local people's voices are heard, the more successful the outcome will be. That will be as important for a conversion, as it was for a closure programme."
In 2007, 45 Devon post offices were closed (12% of the county's total) and a further 38 were replaced by a Partner Outreach programme (10% of the county's total).
As a result of the closure programme in 2007, some Devon communities also had to face the loss of their village shop, difficulties in accessing cash and increased transport costs.
The report uses information gathered from local people, businesses and subpostmasters and views Devon as a bellwether to assess the impact of closures, particularly in rural areas.
Mr Burrows said the experience of Devon showed that local authorities could put a framework in place to mitigate against consumers losing out.
Devon County Council set up a task force after to give strategic support and funding of up to £5,000 a year to 16 villages and set up full-time outreach services, meaning post offices could be run from existing local shops.
As well as financial backing, operators were given practical support and advice on how to develop a viable retail business. While this helped many communities to show considerable resilience to the threat of closures, others without this support didn't fare so well.
The Rural Shops Alliance, which provided retail advice to the scheme, said it had helped cushion the loss of income resulting from changes, whilst enlisting the Community Council for Devon to engage more fully with local communities.
RSA chief executive Ken Parsons said: "The RSA has been delighted to be involved in this successful programme. We are pleased that this independent report has recognised its overall value and of our part in it.
Mr Parsons said he hoped to work with other local authorities to ensure that forthcoming changes to the post office network could be implemented in a way that enabled rural branches to remain crucial parts of their communities.
The full report can be downloaded here (pdf document).
