HOW TO PHOTOGRAPH A PICTURE/PAINTING
Lay the picture on the floor, in a good natural light source, open door way, or window, with no shadows or reflection covering the picture.
Stand over the picture, look straight down, and square it up with your view finder. Take the photo.
Place your picture straight on your easel. Have your easel vertical, not on an incline. Put your camera on a tripod and square up the photo in your view finder. Take the picture.
Transfer photo to your computer.
Crop it in the photo-editing software of your choice. There are some good free ones out there, if you care to google for them.
You can adjust the colour in your photo editing program.
For pencil drawings use the greyscale feature.
For paintings, use the histogram.
To straighten a crooked photo, and it wont be crooked, if you take the steps above, use the perspective distortion adjusting tool.