Think carefully about the DIY approach
It's possible to do it all yourself, but you'll need some pricey equipment, including cameras and film editing software. Basic gear will cost a few hundred pounds, more elaborate stuff several thousand. There's also training and staff time. Matt Locke, commissioning editor at Channel 4 Education, says the DIY approach works if you keep it simple. Sarah Dyer, director of new media at charity Beatbullying, which has taken the DIY route, says the advantage of doing it in-house is the flexibility it offers.
Try to stand out
There are millions of videos on YouTube alone, so be inventive if you want to get noticed. "Quality films that do something different are the ones that stand out," says Georgia Dussaud, head of content at the Media Trust, which works with charities to improve their communications.
Get some advice
If you're a web video virgin, it's worth seeking help from the pros. The Media Trust's free Media Matching scheme could be just the ticket. It puts charities in touch with volunteer media professionals who can advise on almost every aspect of your video. They might even help you to pick the perfect supplier if you ask nicely.
It isn't only about cyberspace
Videos for the web can exist offline as well. They can be put on DVD, for example. They can also be used instead of boring PowerPoint slideshows in meetings where you need to explain your organisation's work, which is what the social enterprise Community Network does when selling its telephone conferencing service to charities.
Be honest with the beneficiaries you involve
Charities often use real beneficiaries in their online videos, but there's a balance to be struck between communicating what they want and producing something people want to watch. So make sure you're clear and frank with them, says Dussaud of the Media Trust: "It's about managing their expectations and letting them know you might not use the entirety of their message."
Make sure you know your aims
Before entering talks with suppliers, make sure you know what message you want to get across, which audience you want to reach and the size of your budget. You should also check whether the supplier has experience of work with charities, has made similar videos to the one you want and how successful their previous work has been.
Jonathan Brigden, producer at design and production company Knifedge, says charities should involve creative professionals early in the process, especially if it's part of a larger campaign, and use their experience to generate the widest possible range of ideas. "Otherwise the options charities can explore could be heavily constrained," he warns.
Web TV is a conversation
"The biggest mistake is to put up a video and then leave it at that," says Channel 4's Locke. "Some think the web is just about distribution, but it's actually a conversation. If people respond to your web video, you should respond to them as quickly as possible. Show them that there is a human being at the other end listening to what they say."
Beatbullying's Dyer adds that you need to be prepared for increased demand if you are successful. "We get hundreds of emails every day from people who want help as a result of our YouTube channel," she says. "We have to think about the channel as part of our services."
Spread it everywhere
Make your video available in as many places as possible. Don't post it only on your website; get it on to YouTube and similar sites such as Vimeo as well. Give people the tools they need to add it to their own websites and post links in online discussion forums.
Rules do apply
Web TV might be more free from broadcasting regulations than terrestrial programming, but rules still apply. "We filmed the teenagers in WHSmith putting slip cases over magazines they felt objectified women," says Channel 4's Locke, who worked with ChildLine on its Headspace web video project. "We had to blur out the faces of customers who did not give us permission to film them."
Although it is geared to broadcast TV, Channel 4 and Five's free Independent Producers Handbook is a useful source of advice on potential legal issues.
Keep it brief
People's online attention spans are short, so keep your videos pithy. "Don't do videos that are longer than, say, three to five minutes," says Locke. "Short videos are also easier for people to share." Dussaud reckons 30 seconds is ideal.
Monitor your viewers
YouTube isn't only a virtual video vault. It has a handy - and, best of all, free - tool called Insight, which tracks who is watching your video and when. This demographic and viewing data can help you to attract more viewers in future.
Get a YouTube channel
Through YouTube's free Non-Profit Programme, charities can set up web TV channels that allow them to raise money through the site. YouTube will also give you more space for your videos and help get your channel noticed. Beatbullying is part of the programme and says the channel helps users of YouTube locate its videos more easily. But you must be a registered UK charity and have neither religious nor political goals to be accepted.
Don't forget animation
Animation can also be a powerful way of getting your message across. "A lot of people think they'll end up with something like Scooby Doo, but they forget there's a great history and range of animation styles," says Brigden of Knifedge. Tom Hadley, a director at the same production company, says animation is particularly good at explaining complex issues such as the credit crunch or mental illness.
And it's not as slow to make as you might think - it is possible to get videos ready within two weeks, says Brigden. Cost will vary widely, however, depending on the style of animation. For example, computer-generated 3D animation is more expensive than hand-drawn images.
- Thanks also to Pat Fitzsimons, chief executive of Community Network social enterprise, and Oliver Rickman, communications manager at YouTube, for their contributions to this article.