Online data thieves are usually portrayed as wily, anonymous hackers who use their cyberskills to crack into our bank accounts. But the most dangerous threats are often the ones we invite. How much information have you willingly volunteered online?

The good news is: it's not too late to keep your disgruntled ex-friends and random nutters at bay.

1. Almost everyone has looked themselves up on a search engine. You may find old bulletin-board posts, minutes from work or volunteer organisations – even links to your social-networking profiles. If necessary, you can ask sites to remove sensitive information or simply delete it yourself.

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2. Click here and complete a request to have your electoral-roll record removed from the site. If you’re concerned that someone has already been trying to collect information about you from 192.com, confirm your fears and name your cyberstalker for a £10 fee.

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Step 2

3. If you’re listed in online telephone directories and don’t want to be, contact your telephone provider to have your details removed. It may take some time for your ex-directory instructions to filter down to all the third-party listing services, so be aware that your details will be available online for a while yet.

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4. Still worried that information about you might be lurking somewhere online? Services such as Garlik will hunt down any visible tracks (get a free 30-day trial and credit report here then advise you on what action you should take to safeguard yourself and your online identity.

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5. Limit the amount of visible public information about you on networking sites such as Facebook, MySpace or LinkedIn by changing your privacy settings. You can make your profile available only to friends, choose not to have it indexed by search engines or block certain users (see How to maintain your privacy in Facebook).

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6. If you've posted photos of yourself on Flickr or Facebook, you may wish to restrict access and not make them freely available to the world at large. You can allow only friends to view your photos, restrict certain albums, or remove your tag from photos your friends have posted.

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7. If you like to post on discussion forums or leave comments on blogs, consider creating an online alias. Choose a username that can’t be linked to your real name or location and that doesn’t reflect an obvious passion. And when you do post comments, don’t give away revealing personal details.

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8. Most sites require an email address for you to register for their services, but don’t use one that reveals your real name or workplace. Try an online email service such as Hushmail.com and, for maximum security, open a new email account for each website (this will also show you if a particular site is selling on your address).

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9. If you suspect that your passwords have been compromised by someone you know, change them. And if you’re using the same password for everything, change that too – there’s no need to do since you can keep track of all your login details with a program such as Steganos' Password Manager.

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10. If someone unscrupulous has had access to your credit-card or bank details, obtain a copy of your credit report from a credit-check companies such as Experian. Experian offers a free online credit report with a 30-day trial, as well as services such as automatic ID fraud notification.

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