It may be the start of a new week but you’ll still find plenty of Black Friday sales as the event goes online for Cyber Monday.

It can be easy to get swept up in the shopping frenzy and end up out of pocket – instead of bagging a bargain.

The vast majority of Black Friday or Cyber Monday offers can be found even cheaper – or the same price – at other times of the year, consumer group Which? has warned.

We’ve spoken to some experts who have shared tips on how to shop both Black Friday and Cyber Monday sales without getting ripped off.

“It’s only a deal if it’s something you genuinely wanted or needed before seeing the discount,” said Sarah Johnson, director of merchandise consultancy Flourish Retail.

She recommends making a list and budget to stick to in order to avoid impulse buys.

“Make the deals work for you by using Black Friday to save on products you already planned to buy,” she said.

“If you stick to your list and stay within your budget, you’ll maximise your savings without unnecessary splurges.”

“When looking to make a purchase, it’s worth comparing the price at multiple retailers,” said Harry Rose, editor of Which? Magazine.

He also recommended using websites that allow you to check a product’s price history over the previous 12 months.

“That way you’ll know a good deal when you see one,” he said.

Which? investigated deals on 227 products at eight of the biggest home and tech retailers in the UK in last year’s Black Friday “fortnight” between 20 November and 1 December.

Its research suggested nine in 10 of the deals analysed were the same price or cheaper at other times of the year.

Mr Rose said you should not feel “pressured to splash out on Black Friday or Cyber Monday purchases as those deals are usually repeated – if not beaten – at other times of the year”.

If you spot something you want to buy in the Black Friday or Cyber Momday sales, search for it on a second-hand platform where you might find it even cheaper, says resale influencer, Jess.

Many resale platforms give you the option of offering a price that matches your budget, she said.

“If you make an offer and it’s reasonable most sellers will accept,” she said. “So not only are you likely to get a good deal in the first place because it’s not new from a shop but you can offer a lower price.”

Vintage clothing influencer Vivien Tang also buys and sells on resale websites.

“I think it is very easy to find almost new or brand new items on second-hand platforms,” she said. “The condition option on listings is now compulsory so it makes it easier to filter for newer items.”

If you’re using the sales to buy Christmas presents you should not rule out buying second hand, according to a new report.

Some 63% of people would be comfortable receiving second-hand Christmas gifts and a further 26% felt neutral about the idea, according to a survey by research consultancy Retail Economics for second-hand marketplace Vinted.

Many people will use a credit card, or may dip into their overdraft, when buying what they consider bargain items on Black Friday and Cyber Monday.

But if you end up paying interest, this could outstrip any savings made on the promotions.

Using a typical credit card to make a £300 purchase, then paying back at £20 a month would take more than a year to pay off and mean having to pay £55 in interest, according to the financial information service Moneyfacts.

Using an overdraft would usually lead to an even bigger interest bill.

A credit card offers more protection when buying something over £100, so there is greater chance of a refund if something goes wrong.

Financial experts say paying off a credit card immediately, perhaps from savings, before any interest is accrued, is the safest option.

Criminals use the hype around Black Friday and Cyber Monday to try to steal from online shoppers.

Purchase scams are when someone is tricked into sending money via a bank transfer to buy something – often advertised online or via social media – that doesn’t exist.

The number of purchase scams soared by 29% around Black Friday and Cyber Monday last year, according to analysis by Lloyds Bank.

The bank’s fraud prevention director, Liz Ziegler, said: “When shopping online, the best way stay safe is to buy from a trusted retailer, and always pay by card for the greatest protection.

“If you’re unable to do those things, that should be a big red flag that you’re about to get scammed.”

You should be wary of fake websites and check the web address belongs to the official brand before you enter any financial or personal information, according to Which?.

Beware of posts from a newly-created social media accounts, or links to a recently-created website. You can use verified domain checkers to confirm when a website was created, Which? said.

It warned against buying at “too good to be true” prices because if something seems too good to be true, it likely is.