Four Rules of Description:

Observe carefully. Look at the world around you. Doing this will give you the most benefit when writing a description.

Form a central impression. What do you see, in general, when you observe. You may note that a person's room is very messy. This is your central impression.

Now, select specific, concrete details to support your impression. In the messy room are three pairs of dirty socks strewn across the floor. On the desk, a brown banana skin is beginning to grow a dull green mold.

Finally, organize your details. For a messy room, you might start with eye level, then move to what you see on the floor. 

Example : A Special Haven

      One place I like is the haven I find inside my car while I drive to or from my work. I'm sure many people are the same as I am when it comes to the car "cocoon." Here, I enjoy the radio personalities on the CBC: in the morning, Rick Cluff; at noon, Mark Forsythe; in the evening, Jane Farrow. It 's like being in my own private living roomI can laugh at their jokes, even sing along with the music they play. You may have noticed people like me, singing by themselves in their cars! In my Corolla, I even like the warm aroma of the plastic, either baking under the hot sun, or coming from the heater at my feet. A car is like an old shoe, sometimes, full of interesting smells. I even like the smell of gasoline that lingers after filling up, especially when I've gotten the best price of the week. The inside of my car, while I drive it to work, is really a great refuge, and it gives me the opportunity to both get ready for work and to prepare for my life at home, away from the demands of daily life.

Assignment 1:

Think of a place you either dislike or like very much. Observe the place (in your mind) and form a central impression. Select at least three different details that support your impression. Describe it carefully in a short paragraph form.

Assignment 2

Choose a person you know very well. Spend five to ten minutes writing down an example for each of the three headings below.

Do not use any general words, such as "untidy," "hardworking," or the like. Let your descriptions tell the story. Your fellow students should have a clear idea of that person's character from your indirect description.

Be sure to clarify any misunderstandings and help each other to improve your descriptions.

Physical characteristics:

(E.g.: He is a small man, with unkempt hair, whose trousers were patched at the knees.)

Behaviours:

(E.g.: Whenever he disagrees with me, he stands, arms across his chest, chin jutted out. Then, he waves his finger at me and says, "You have no idea, no idea at all.")

Anecdotes:

(E.g.: Once, when hiking, we were trying to find our way down from a mountain. John clambered down and began slipping towards a sixty foot cliff below. I said to him to hold on a second, put down my pack, held onto a sizable root and pulled him back up.)

Assignment 3

Pick a favourite place and remember four details of the smells present there.

Food smells, household smells, cooking smells, if the place you remember is a home.

Outdoors smells in nature, while combined with a walk in a beautiful place, often produce strong memories as well. List the four smells before you begin your paragraph.

Write the memory. Include at least one other person who was present at the place you remember. Mention three smells. Keep your paragraph short, so you can finish in 20 minutes or so.

source  http://palc.sd40.bc.ca/palc/bcassign/advanced.htm