I am not sure what you are practicing currently to see aura. Here is a simple and effective method of seeing aura for the first time:
Situate the person in front of a very softly illuminated PLAIN WHITE background. A color background will change Aura colors, so you need additional knowledge about combining colors. Some combinations of background and Aura colors may cause misinterpretation problems.
Choose ONE SPOT to look at. The middle of the forehead is VERY GOOD. This is a location of so called Brow Chakra or the Third Eye. In some cultures (India) they put a mark on a forehead. Such a mark in ancient times could mean the invitation to look and see the Aura.
Look at this spot for 30 to 60 seconds or longer
After 30 seconds analyze surroundings with your peripheral vision, while still looking at the same spot. Continuing the concentration is most important. Resist temptation to look around. You should see that the background nearby the person is brighter and has a DIFFERENT color than the background further away. This is your own perception of the Aura. The longer you concentrate, the better you will see it. Remember, concentration on one spot increases your sensitivity by accumulating the effect of the Aura vibration reaching your eyes.