i focus on what's directly behind the individual, like a wall or other object.
If you want to get really good and expand the psyche to another level here are a couple other pointers.
Record some affirmations, for example "i see auras with ease at will" play it with some binary beats that bring the mind down to at least 40 hz, preferably about 13 hz or less when you go to sleep or when you wake up in the morning for at least 30 minutes. You want the words to be quiet in the background so you can barely here them like a whisper.
Pick up a small book on the subject. You can read one in a day. And get some good examples of what the colors represent.
A couple years ago i was expanding my third eye to the point i saw energies flutter and dance during work training that lasted about an hour a day before we opened. i would watch my boss at the podium and listen to him go thru the motions of the day and watch energy patterns and electronic wave like anomalies whisk briskly in the background. i spent a great deal of time back then expanding my mind via subliminal programming, self hypnosis, practice, affirmations playing in the background of binary beats custom audio i created. And a few other mind tricks. lol

This is subliminal programming of the mind and it helps activates your psychic mind aka third eye.

lol on the grey goo!