The NCVO has launched a campaign backed by Prime Minister Gordon Brown that encourages people to give money to their favourite causes.
The web and PR campaign, called What Do You Believe In?, asks people what is important to them and to consider what they are going to do about it.
It also gives people four pointers to help them donate to charity.
"I believe charities make a huge and positive contribution to local communities, which is why I'm backing this campaign to support thousands of organisations across the UK," said Brown.
Stuart Etherington, chief executive of the NCVO, said lots of small donations made a big difference to voluntary organisations. "If everyone gave just £1 more a week, we'd raise an extra £3.1bn to help thousands more people," he said.
The campaign advises people to use online fundraising initiative The Big Give and the Charities Aid Foundation website to identify organisations working in areas of interest, and to research them by visiting their own websites and that of the Charity Commission.
It also urges donors to consider local as well as national causes and apply for Gift Aid on their donations.