Consumers are being warned they could be put on a "suckers" list if they respond to unlikely offers promising large sums of money.
Some scams refer people to premium rate phone numbers
The Office of Fair Trading says that if people take up offers their details could be sold around the globe, leading to a deluge of scam letters.
Fraudsters are becoming increasingly sophisticated, it says.
OFT is launching a campaign to help people to identify scams so they are not caught out in the first place.
BBC correspondent Richard Scott said that just as legitimate companies might share data with each other, now so do the fraudsters.
Most scammers would advertise easy ways of making money, he said.
They would then want cash up front or imply that something has to be bought in order for the prize to be claimed, he added.
As part of the OFT's month-long campaign, which will be officially launched on Wednesday, more than half a million leaflets and posters will be distributed through libraries, community groups and police stations.
OFT advises people to be sceptical, to not send money or give out personal details and to contact trading standards, the Citizen's Advice Bureau or the police for advice.
Penny Boys, OFT executive director, said: "Our campaign aims to equip consumers with the skills and knowledge to recognise scams, whatever their form, and to prevent themselves and others from falling victim to persuasive and manipulative approaches."