The document, Paving the Way, will outline the commission's views on councils' responsibilities and dealing with change as power shifts from the old to the new authorities.
The guide was aimed at councils uncertain of how to manage the transition, said Mr Foster.
Councils needed to set out a proper project plan for ordering any changes involved in reorganisation, he said.
'We are offering a model for those councils who haven't done that thinking on the future so far.'
At best local government reorganisation offered the chance of better servcies at lower cost, he said. 'At worst we have a real chance of damaging services.'
Councils should take a proactive attitude to change rather than negaitvely reacting to or resisting change, Mr Foster urged.
A negative attitude ran the risk of leaving constituents without proper services as new councils took over with inadequate preparation, he said.
Vital planning issues included transfer of records, ensuring the compatibility of computer systems and keeping staff well informed. 'The amount of motivation that is lost when morale falls is massive,' he said.
Mr Foster urged financial prudence on the part of outgoing councils. 'Outgoing authorities should be careful about spending tomorrow's money in advance.'