Computers and the internet are wonderful for children. Children can research things for homework, join fun and obscure clubs with people from around the world, play games that stretch the mind and imagination and produce great school projects that make what today's adults did at school look like junk.

However, computers and the internet can also be dangerous for children. Children can access obscene or otherwise offensive sites containing things that children just don't need to know about or see, they can be targeted and groomed by creeps, and they can miss out on exercise or proper face-to-face friendships while spending time sitting down in front of a screen.

So what's to be done? How do you get the advantages of computers without any of the nasties? Here's a few quick and easy ideas that anyone can do to make children's computer use safer.

Limit daily "computer time" or even screen time. Half an hour of computer games done for fun, plus any time needed for homework.

Keep the computer in a high-visibility area of the house (i.e. not in the bedroom). Children (and adults) are less likely to sneak onto forbidden sites if anyone can wander past and see what's going on. This can also make games a bit more social – spectators can cheer, commiserate and offer advice.

Search engines are wonderful but they can sometimes throw up unsuitable sites. It's all too easy for a child to try to hunt for something innocent and get something ghastly (examples of things that little girls have run searches for with unwanted consequences include "beauty and the beast", "rainbow fairies" "sleeping beauty" and "I love horses" – need I say more?). Some engines, such as Google, allow you to filter the sites the engine will suggest.

The policy in this writer's household is that children have to be able to give the URL of the site they are visiting to their parents or housekeeper London. They should explain where they got it from – before visiting it. This avoids the potential problems of accidentally stumbling onto an unsuitable site.

Don't allow children to give out personal information over the internet. Definitely, phone numbers and addresses should not be given, although nationality and name are OK. Whether age should be given is debateable. Remind children that not everyone on a forum or chat room is who they say they are. Having said that, the idea of using a fake name and filling out sign-up forms with daft information appeals to some children's sense of humour. Make it a policy for children to ask for permission first before signing up to anything.

The software packages that blocks sites with certain words in the content aren't all that good and can be a downright pain. For example, heavy-handed programs that block anything with the word "sex" will block perfectly good sites about biological research and even tourist sites about Sussex, while things blocking "rape" will block sites about canola and the use of rapeseed oil in producing biodiesel.

If you're unsure, check the "history" of your browser to find out where people have been.

Use common sense when buying games for children to use. The ratings on the front can be helpful, but occasionally you get lunatic ratings where a "duck shooter" type program gets the same rating as a war game (it happens). To be certain, test drive any games rated higher than G yourself in private to make sure that you're happy with what's on it (the perfect excuse to spend the night playing Age of Empires or Midtown Madness...).

Get good antivirus and antispyware protection – it's only too easy to pick up tracking cookies and similar, even from "nice" sites.

Talk about what's going on online, whether you're suspicious or not. This keeps communication lines open so if your child does stumble on something awful or have someone in a chatroom or forum send them unsettling messages, you can talk about it (and know how to deal with it).

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