Having been baptized in the pool of scam artists, I can recommend the following:
1. If you get a big red message on your computer screen, just delete it or restart your computer. It will go away.
2. If you get an email or phone call, claiming that you owe a certain amount of money, ask them to send a letter. If it's a scam, they won't bother and will go away.
3. If it's one of those "You just won a million dollars (pounds) and just send a thousand because you must pay the taxes first or you won't get the million" scams, keep in mind that when you really win the lottery, THERE'S NO UPFRONT FEE! Just hang up the phone or delete the email and they'll go away.
4. Oh my, what serendipity!! The phone rang with the guy (with an accent no less) wanted to give me a refund on a computer program fee And having had this conversation previously, I knew that he would say that in order for him to process that refund, HE WILL NEED TO GAIN UNLIMITED access to my computer. So that scam is not money, but the unlimited access to the computer, something more valuable than mere money. And of course, I just repeated the golden phrase "send me the check" a couple of times, and he went away.
So if someone is on the phone or sends an email requiring immediate action, PUT THEM OFF. If it is too good to be true, it is too good to be true. If nothing else, delete the email or hang up the phone. Anyone with a legitimate refund, bill, lottery win, etc. will be glad to follow up with a letter.