Almost half of trustee appointments come through personal recommendations, a survey by the Institute for Philanthropy has suggested.
The organisation questioned 100 chief executives and chairs of the boards of UK charities for its report The State of UK Charity Boards, and found 49 per cent of all trustee appointments came through personal contact.
Only 20 per cent of respondents said outside advertising was their primary means of trustee recruitment.
The report also found that 42 per cent of respondents were on boards that did not review their performance internally every year, and 72 per cent were on boards that did not undertake external performance reviews.
"Boards which evaluate their work as thoroughly as possible, with clear references to outcomes and benchmarks for achievement, stand a better chance of attracting part of the government funding," the institute said.
The report also found that respondents thought fundraising expertise was the skill most lacking on their board. Despite this, fundraising was the second most common area of expertise among board members, with 65 per cent of trustees having fundraising knowledge, and 81 per cent having finance experience.
The report's top recommendation for boards was that every trustee should be involved in fundraising for the charity. It said many donors felt that "a charity that is most effective is one where every trustee is actively involved in maintaining its financial health".
Salvatore LaSpada, chief executive of the Institute for Philanthropy, said the story of the report was "good so far, but had room for improvement".
"In an era when donors are increasingly looking for greater evidence of positive social impact by the charities that they fund, it is important for trustees to evaluate clearly their work, regularly reviewing even their own performance," he said.
"And given the areas in which trustees feel that they lack skills, we would recommend that they recruit more widely, across a range of disciplines, skill sets and industries, in order to address these requirements."