From an article at TVPeople.info:

I often get many emails from people asking me how to get a job in a TV Art Department.

Most people track me down through my website www.setdesign.tv and because it's really designed as a showcase for my work, doesn't really offer any advice. I almost always respond to every email with a short message offering some basic help. It's very easy to spot the time wasters, and I just don't write back to them.

The people that are really interested, will write back, and then I know they are serious.

To get into TV, you need to have a passion for it, a yearning to get involved, and willingness to work hard.

I was that person when I started out. I was ambitious then, and would write letters to all sorts of people. Big-Wigs in the Film Industry, celebrities, in fact anybody I thought might be interested in my plight. Some responded, most didn't, but I had an enormous spirit to work in the business and achieve something.

Fundamentally, you need to have some skill and some artistic background.

The more you can do, the easier it is to employ you.

It's good to have some technical drawing skills, and be computer literate.

You need to be artistic and creative.

Being able to drive also helps.

I came from a Fine Art background and taught myself technical drawing, so not every route is the same.

The next most important thing, is that you need to be nice. Getting on with people is a huge part of your work. The rest is ability and talent. Nobody will employ you if you're not a nice person.

The first thing I would advise, is target the right people. (check out tvpeople.info)
Don't write to Directors or Producers or Production Companies.If you want to work in the Art Dept. The people that employ you first off will be Designers. When you're a Designer, then you can write to Producers.
The best place to start, is your TV. Watch the credits of shows you like, and make a note of the Designers. Then do a google search to see if they have a website.
There's also a directory called The Knowledge. It's expensive, so try to borrow one, and get the contact details of Designers that interest you.
I think you can subscribe to it online if you're not in the business: www.theknowledgeonline.com/ or www.kays.tv is another directory.

Next, be persistent, but not overly so.

I will almost never meet up with a student or new person unless a) Something remarkable catches my eye in their CV, b) Their email has a quality to it that needs following up c) They badger me. It's a very fine line between badgering and becoming a pest, and I'm afraid I can't tell you what that is. You need to know it yourself, otherwise you're annoying and I probably won't want to see you!

Timing is also crucial, and sadly completely out of your hands. I recently had a CV from a petty cash buyer, three days before I needed to find a new petty cash buyer. Sometimes luck does play a part.

Once you've made contact with a Designer, it's important to know that your first job in the business, will not be as a Designer. I get many emails from people asking how to become a Designer, and they want to get work as a Designer.You do need to realise that your first job will probably be low paid, and you'll be doing runner type work. Be ambitious, but be realistic. In a mixed metaphor kind of way, it's a long hard road up the ladder. Write to Designers and say you want to work in the Art Dept. Don't tell a Designer that's worked his whole career to become a Designer that you want his job.

I've also had letters from people wanting to be Directors....know your target audience.
Also write to people in the type of work you're interested in. A Theatre Designer will have not have much work in the LE sector (usually), so research the route you want to take.

Don't expect huge wealth. Budgets are getting smaller, and crews are shrinking. It's not a great time to start off in any business, and the TV Industry is no exception. You can expect to be paid anything from £350-£450 per week as an art dept assistant starting out.

So in summary:
 
Have the right skills, and have many of them. The more you can do, the easier it is to give you a chance.
 
Write to Designers in the field you're interested in (TV & Film generally don't mix)
 
Send an email that shows you're interested. Be relaxed and be yourself, and show your passion.
 
Be persistent but not pushy or over-confident.
 
Make sure you meet face to face. This is so important I cannot stress it enough
 
Research the business, and try to find out what people's jobs involve
 
Be willing to work hard and long hours
 
Have an amenable character
 
Have a real passion to work in the business
 
Try to work for a number of Designers if possible to gain a wide range of experience.

I have a really fantastic Art Dept that I use on a regular basis. Consequently, it's very very hard to get work with me, because I tend to hang on to all the good folk that work with me. Having said that, sometimes some of my team are busy and I need to look elsewhere, and sometimes I'm so busy with jobs that I need more people. Please feel free to write to me, but I'm afraid I can't promise to see you or even to employ you. But you never know....

So that's it. Life in the TV business.

Rewarding, rarely glamourous, arduous, but if it's your thing, it's the best job in the world

(You can follow my daily tweets on Twitter: @jpgdesign)