Below are some basic tips for taking good photographs of your art, whether it be to email your teacher or to create a copy of your work to send to your gran.
Get your angle right:
Lighting your painting:
Natural light is best, as artificial lights tend to alter the colour of your artwork. However, if you have daylight bulbs you can angle your lights at 45 degrees from both sides, which will result in an even distribution of light and reduce glare. 
Here are some more tips:
• Use a tripod if you can't. keep your camera steady.
•  If you have a grid on your camera's viewfinder or on your phone, use it to check that you are not looking from an angle. This will help to prevent distortion.
• Use daylight where possible to avoid the lights in you home from casting a yellow tint over your picture.
• If you are using a wide angle lens, you may need to step back and zoom into the artwork to prevent lens distortion. But if you are using a cameraphone, you may need to avoid zooming as the resolution is reduced with digital zooms more than optical zooms.
An advanced guide to photographing your artwork:
Emailing your Art
Be careful when emailing your art that you don't compress the images. If you are using an iPhone, you will probably be given the option to send your images as Small, Medium, Large or Actual Size. 
Always send it as 'Actual Size' if you can. 
If you are worried about having enough data on your phone, wait until you are connected to Wifi.