This Letts Revise GCSE Additional Science guide is in excellent

"Only access Gumtree from gumtree.com and do not follow links sent by other users"

"Share photos and ask lots of questions about the items you are buying and selling"

"If an ad or reply sounds too good to be true, it probably is"

"Use the 'Reply to ad' button for your safety and privacy"

"Don't reply to email addresses hidden in text and pictures"

"Beware of fake Gumtree, eBay or escrow sites and invoices"