This will show You how to start drawing using a photo as a reference, once you've decided to draw. ALWAYS credit the artist if you are drawing from someone elses artwork and verify if the artwork is prohibited from copying.
First of all, you need to decide what are you going to draw. A good place to look for images is www.deviantart.com however you MUST make sure you have permission and that the artwork is not copyright.
You have to enter a keyword and look for an image you like. I decided to look for mushrooms.
After you select an image, please chek if the owner hasn't prohibited the use of his artwork. (Also a good idea is to reproduce your own photos)
If you are not shure, weather the owner alows you to use it, mail the owner and see if he minds. Most of dA users are fine with that as long as you ad a link or say that your image had a ref...
Then copy the image you have chosen.
Paste your copied picture into paint.
Open the "Create a new drawing" and adjust the size of the window, so you can see the original picture.
Start by drawing a rough background using the filling tool.
Don't pay attention to the detail. Just try to get the colours right.
Continue the same way.
Try to alter the same colour a little bit or give the next filled area some transparency.
After you have done the background more or less, fill the white areas with a darker colour(except the spaces where your main drawing will be).
Never use more than 15% of ink on the background!!!
Aftrwards start drawing your main detail, but the same way you did the backround - very roughly.
Then you can start adding shading and detail. At this point you can use any tool that suits you. It also depends on the picture you have chosen.
After you have aded detail to the pic you can use the ink where ever you think it is most needed.
(NOTE: This last picture has been made using PhotoShop. I have been experiencing trouble with my PC/RMD lately, so it won't allow me to save pictures. I was very tired, so I didn't finish this drawing, however, I suggest you to save your picture once in a while.)