Fraudsters are targeting pensioners and struggling households among an estimated four million victims of scams each year, according to Citizens Advice.
The charity has warned that the elderly and those struggling the most are facing an "invasion" through their computers, phones, letterboxes and on the doorstep from fraudsters.
Fraud offences in England and Wales rose by 25% in 2013 compared to 2012, with 207,252 cases reported to Action Fraud.
But Citizens Advice said up to four million people could be scammed each year as many incidents went unreported.
A study found a third of scams (34%) were over the phone, a quarter (24%) were through visits to a website, 16% were via letter or fax and 10% were through emails.
Counterfeit cashier cheques, fraudulent lenders offering loans to get hold of personal details, dating scams, ticket cons and computer hacking were among the most commonly reported examples.
Online shopping and auction fraud was the biggest single type, with almost 40,000 recorded cases.
Citizens Advice, Citizens Advice Scotland and the Trading Standards Institute have launched Scams Awareness Month and are urging people to "fight back" against fraudsters.
They warned consumers to be alert for non-secure websites that asked for financial details and to be aware that scammers operated via the phone and on the doorstep.
Citizens Advice chief executive Gillian Guy said: "Scammers are picking the pockets of millions of innocent people.
"Pensioners and hard-up households face invasion through their computers, phones, letterboxes, and on the doorstep.
"People who are already struggling to put food on the table, let alone save money day-to-day, are being fleeced of their hard-earned cash.
"It is disgraceful that scammers are often targeting elderly people with sophisticated scams such as posing as their bank or phone company.
"Every day, Citizens Advice staff and volunteers hear from people who have lost out after being tricked.
"We are running Scams Awareness Month to encourage people to fight back against the fraudsters pushing their cons into the nation's homes by reporting those scams."
Citizens Advice Scotland chief executive Margaret Lynch said: "Across Scotland, CAB will be getting out into their local communities to highlight to people how they can beat scammers.
"That means being more vigilant, spreading the word and reporting any scams that people come across.
"By doing this we can help people avoid scams and importantly ensure the authorities can take action to stop scammers in the first place."
Trading Standards Institute chief executive Leon Livermore said: "Scams Awareness Month gives Trading Standards and partners like Citizens Advice the opportunity to reach out to those most at risk from scammers, and educate them and members of the community as to how to avoid falling victim to these insidious schemes."
Consumer Minister Jenny Willott said: "Scammers prey on the most vulnerable people in our communities, often leaving them distressed and out of pocket. Not only do people need help and support if they fall victim of a scam, but they also need to know where to turn to find out how to avoid falling victim in the first place.
"This is why I am delighted to give Scams Awareness Month my full backing as part of our ongoing battle against scammers. The activities Citizens Advice are planning mean consumers will be better equipped in spotting scams and knowing where they can go for help and advice."