Learn How to Draw:

First and foremost you need CONFIDENCE. You need to believe that you can do this. You can create beautiful sketches. You will need PATIENCE. Understand that this is not something that most people will become great at in an hour, it takes TIME to learn how to draw like a professional. Also it is okay to make mistakes. There is nothing wrong with erasing parts of the drawing over and over again, or even tossing out the drawing completely and beginning again.

Now that you are ready to begin, Start off sketching simple items. Create a page full of small, thumbnail sketches of that particular item, don't be afraid to try out 
different techniques. 
Once you have found the technique that best suits you, try to focus on a particular part of the item that you find interesting. Sketch only that  portion of the object.
Once you have focused on one interesting area of the object, try a different area that you find interesting or try to sketch the entire object. You will find that there are many different techniques and styles to sketching. One way may work better for you than another.  Each person will be different. I will try to give you some different ideas and ways to sketch.
  To see more examples go to the gallery of sketches.