If you are replacing windows, take the opportunity to install new ones that are certified to British Standard BS7950 'Windows of Enhanced Security' and consider using laminated glass, particularly in ground-floor and accessible windows, as this is much harder to break.

If you don't have a window in the door or some other way of checking who's calling, fit a door viewer. Look through this to identify callers before you open the door.

Check that the door hinges are sturdy and secured with strong, long screws. For added security, fit hinge bolts. These are cheap and help to reinforce the hinge side of a door against force. Hinge bolts or security hinges are especially important if your door opens outwards.

Never hang a spare key inside the letterbox. This is an obvious place that a thief will check. Letterboxes should be at least 400mm (16 inches) from any locks. Consider fitting a letterbox cage or other restrictor, which prevents thieves from putting their hands through the letterbox and trying the latches from the inside.

Most front doors are fitted with a rim latch, which locks automatically when the door is closed. You can open these from the inside without a key. For strength and quality, look for BS3621 Kitemarked products. For extra protection, you should consider installing the following.

This locks automatically when the door is closed and is more secure than other types of rim latch. It needs a key to open it from both the inside and the outside.

Buy a door bar or chain and door viewer. Use them every time someone calls. Remember, though, that you only use the door chain or bar when answering the door - don't leave it on all the time.

Fit a five-lever mortise deadlock about a third of the way up the door. Most insurance companies are happy with one Kitemarked toBritish Standard BS3621. You can only open a deadlock with a key, so a thief can't smash the nearby glass panel to open the door from the inside. Deadlocks also mean that if burglars get into your home through a window, they can't carry your belongings out through the door.

Sliding patio doors should have anti-lift devices and locks fitted to the top and bottom to stop them being removed from outside, unless they already have a multi-locking system. Get specialist advice. If you are getting new or replacement patio doors, ask the system supplier for their high-security specification.

Never leave a spare key in a convenient hiding place such as under the doormat, in a flowerpot or behind a loose brick - thieves know all the usual hiding places.

If you move into a new home, change the front and back door locks immediately - other people may have keys that fit. Look in your phone book for the names of local locksmiths who are members of the Master Locksmiths' Association.