There are many different technique that advise how to see aura, however the most common appears to be looking pass the object of attention. It is difficult to describe in creating but an attempt will be made regardless.
Pick an object. Look at the object at all angles then stare past the object making your eye less focus. If you start to see fussiness around the object that is definitely indicate your doing well. Also if you are able to see colors around the object that are not there, then you are successful in discovering aura around the object.
Many recommend that you place a white sheet of paper behind the object when begining so it can cause less amount of interference. But do what's better for you.
How to see aura