All life, thoughts, emotions and matter are energy. If you work at it you can train your eye to see this energy. Different people can see it to different degrees, and I myself am still working at it even though it's a talent that came to me quite naturally.
Lighting is crucial when you're first starting out, and even when you become used to looking for this kind of energy it's still difficult on say a bright sunny day. Start off slowly, because it can be easy to strain your eyes trying to see something.
Low light conditions seem to be best when looking for energy, and somewhere with a plain background can be helpful as busy backgrounds tend to distract the eye. As a first experimentation hold your hand out in front of you. So what are you looking for, huh? Well, to start with you're just looking for a fuzzy sort of outline going around the outside of your hand. It will probably only be a few millimetres or so wide.
And how do you go about looking for it? The best way I can explain it is that it's like trying to look at one of those 3D hidden image pictures. You need your eyes to unfocus to a certain degree because you are trying to look inbetween the physical spaces that your eye can see quite naturally. To begin with this energy will look similar to watching heat rise off the road on a hot day. Like I said, don't push it because it's so easy to strain your eyes. If it's not coming, just try again later.
When you first manage to see this energy the chances are that you'll be so chuffed that your eyes will snap back into their normal way of 'seeing' but the more you practice the easier it gets.
After you've managed to master finding energy this way you can start to look for colour in this energy. What sort of colour does the energy around your hand appear to you? Don't push your eyes, they do need time to pick this up and it isn't easy to hold onto the colours your eye is picking up in the beginning.
When you've started picking up impressions of colour you will probably start to notice that you are starting to see another band of energy surrounding the first band. When you get this far you might want to do some research on the auric field and its assosiated colours.
For extra practice here are some other things you can try. When you're talking to someone see if you can notice a field of energy around the persons head. For some reason it seems to be easier to see energy around the head. The band of energy will appear much larger than it does around your hand. You probably won't see colours unless you've gotten rather good at this because it's hard to look around somebody's head during a conversation for too long without making them wonder what you're looking at!
At dusk or dawn time see if you can notice a field of energy around trees. Needless to say the energy field will be much larger. Try to do this on a still day as branches waving around in the wind can be very distracting!
And, maybe surprisingly, try looking for bands of energy down the sides of cuboards, chairs etc. In low light conditions it can be quite easy to pick out bands of energy running down the straight lines of furniture!
Now what's the point in all this you wonder, right?
Once you can 'see' energy in this way you can start looking for energy patterns of non-physical things. I personally find this more easy inside a building than I do outside. Beware though, and make sure that you do really want to see as this can be... disconcerting shall we say?
In some ways it can be easier to do this but of course you have nothing physical to concentrate on. I personally found this easier to master than finding the energy of physical things. To look for energy in this way you have to focus inbetween places. The easiest way to do this is to pick two physical objects and focus on the empty space between these two things. Your eyes should focus on the inbetween spaces by doing this. Don't try to move your eyes around or they will quickly try to focus on something tangible. Instead keep your eyes still and use your peripheral vision to scan your surroundings. Are there any blocks of energy that stand out to you? Take this slowly and give yourself time to find your feet and understand what you're seeing.