How Do You Know If You Drew Something Right?

There is no specific rule on that. Drawing or painting is a free form of expression. You can draw anything you like and put a name on it, this is freedom. And as a rule of thumb, when you make something right, you feel its right as it looks right.

The technique I use for drawing a detailed replica of an image (photorealism) is called grid drawing. Basically what you do is take the photo of what you want to draw and draw horizontal lines with a ruler depending upon the size of the picture, and then draw as many vertical lines through the picture, then, LIGHTLY and in pencil draw the same grid on you paper in the size that you desire, with the same amount of lines, take each little box, starting from one corner and copy the fragment into the box on your paper. It scales down the image and lines so that you're basically just drawing simple shapes and doing basic shading. I am going to look up a link to show you an example. Like all drawing though, it takes practice, that is why they call it an "art" it wouldn't be so amazing if it was easy now would it? Every artist will tell you that they practice and put much time and effort into their pieces. So... Here is are a couple of links with visual examples. Best of luck!

drawsketch.about.com

drawsketch.about.com