When you buy something on the internet, you're often dealing with a company you've never heard of. Sometimes you're dealing with someone you know, such as John Lewis, or Harrods, but all too often you're buying from a complete stranger.
How do you know if they're kosher?
You can't go by how professional their web site looks - anyone can spend £50 to get a nice-looking web site. But there is one important test that you can apply.
Do they give a phone number?
In my experience, every reputable company will give a contact number that you can call. If a company doesn't give a phone number, then that doesn't mean that they're scammers, but certainly scammers are reluctant to give a phone number, for obvious reasons.
So I make it a rule - I never buy anything from a company that doesn't give a phone number on their web site.