The Fundraising Standards Board is to launch a manual, an advice line and a sheet of hints and tips to help charities improve the way they handle complaints.
The sector's self-regulation body is introducing these measures because it is concerned that many fundraising organisations do not have formal complaints procedures or fail to recognise the value of dealing with complaints effectively.
"Good complaint-handling is often the unloved and under-appreciated side of fundraising," said Alistair McLean, chief executive of the FRSB.
"However, it can retain and sometimes increase a donation, build donor relations and secure future donations. Poorly handled or ignored complaints will inevitably lead to the loss of donors.
"Complaint-handlers often have a rough ride, but we hope these measures will support them in their role."
The hints and tips sheet and the manual on how to deal effectively with complaints will be given to charities when they become members of the FRSB.
The 515 FRSB members that submitted returns for 2008 received 26,349 complaints. Almost 20,000 of these were about direct mail.
A spokeswoman for the FRSB said: "Many non-members have yet to introduce a formal complaints process or to recognise the importance of this aspect of donor relations." She cited a 2005 Charity Commission study that revealed that about 30 per cent of charities did not have formal complaints processes.
The FRSB initiatives will be launched on 7 July during the Institute of Fundraising's National Convention, so that charities that are not members of the FRSB will also have access to them.
The FRSB will then compile feedback from charities about how useful they have found the measures and decide whether to roll them out permanently. It is likely the manual will be reproduced on the organisation's website.
McLean and representatives of Cancer Research UK and Which? will deliver a seminar at the IoF Convention on how best to record complaints, measure improvement rates and build complaint-handling into everyday activity.