In the wild, you will notice the complete absence in some man-made shapes, for example- triangles and squares. This is because almost nothing in nature is symmetrical. To a human being, the single most distinguishable object in the world, is another human being. So what you want to do is to break up your shape and blend in with the background. Firstly make sure that you are wearing DPM, or some other type of camouflaged clothing, this already begins to break your shape up and blend you into the background. Now to look like swamp thing : put two to three elastic bands at uneven distances around each one of your limbs. Now look around on the floor in the type of area you will be hiding in, e.g. ferny, long grass, short grass, etc. Now say you are in an area of long grass, about two or three feet high say. Rip up some of the grass and put it under the elastic bands. The most important thing you must remember while doing this is what it will look like when you lie down. Ideally when you lie down you should resemble some kind of green porcupine, everything should be sticking up, as it would be in nature. Once you've done your elastic bands start stuffing it everywhere, in your webbing, your hair/hat, you boots, anywhere. The basic reason for this is so that when you lie down and crush all of the grass underneath you, there is a still load sticking up in the air to fill the gap. Bear in mind, that if you are travelling through lots of different types of terrain then you will need to keep changing the foliage you are wearing.
I suppose that sky-lining comes into this section as well. Never, ever go along the top of hills or ridges, if you need to walk near the top of a hill then stay 5- 10 meters off the peak. If you walk along the top of a hill then you will stick out like a sore thumb. Think: nice smooth hilltop...tree...tree...walking person making himself very obvious by framing himself against the sky. If you are off the skyline then you immediately become 10 times harder to spot as you are blending in with you surroundings. Also never look over something if you need to see what's on the other side of it, look around it. This is for the same reason, your head will stick out a mile if you start poking it over rocks and mounds, much less obvious to look around the side.Basically you need to remember to break- up the shape of anything man made and recognisable, including yourself or any vehicles you may have lying around.
Believe it or not, your skin emits a shine reflected from the sun or moon, that the human eye can detect quite easily. You need to eliminate your skin's shine as well as on anything you might be carrying. To eliminate the shine on most of your clothes is very simple- wear Trousers, boots, long-sleeved top, some kind of scarf or scrim netting, a hat and gloves will cover a very large proportion of your skin, usually leaving only your face. Obviously make sure that you clothes are camouflaged. To eliminate the shine from your face use a camo head net. So that's the shine from your skin gone, now shine from things you might be wearing/carrying. If you are wearing a watch, either take it off or make sure it is well covered, though it might be very amusing to shine light in someone's eyes, they will see you, and probably shoot at you. Any jewellery, glass objects (e.g. bottles) should be in a nice bag or a pocket, just use common sense. Now if you are wearing a nice pair of boots that are your pride and joy and you regularly polish them you aren't going to like this. You need to get a few handfuls of mud and grit and slap them all over your gleaming, brand-spanking new boots. It seems a shame, but I assure you they clean up to what they looked like just before (honest). They are also probably black, and pure black doesn't naturally occur in the wild. Follow those steps and you have just eliminated shine.
This is more important than you might think. You need to constantly be aware of where your shadow is, or it will betray you. If you are hiding behind a few meters behind a bush and the sun is to your one of your sides, and someone is on the other side of that bush, they will see your shadow behind the shadow of the bush. The best way to deal with this is to get into shadow that is already there and get as low as possible. This will eliminate almost all of your shadow.
Quite obvious; keep sound to an absolute minimum. Anything you have on you that rattles, or squeaks or thuds and bangs when you walk or run must be sorted out. Put a cloth or clothes around anything that rattles, oil anything that squeaks, and soften anything that thuds of bangs. You should be able to jump up and down and only hear the faint sound of your boots hitting the ground. Don't talk and use hand signals, or some other arranged code to whomever you wish to communicate with. This applies especially at night, because people's sight won't be as good their other senses kick in with style, especially listening. If you are in a group, make sure that everyone gets the messages or signal.
If you are hiding, keep as still as you possible can. Take long, deep, controlled breaths, move absolutely nothing. The human eye will immediately pick up movement . So get comfortable before you settle down. If you have an itch, don't scratch it, if you need to take a leak don't. After all there maybe someone else who is hidden an looking for you. Move only when you are sure that there are no enemy in the surrounding area. Movement will also scare the wildlife, it will either make them very, very loud, or quiet .Use your common sense and stick with these basic rules and you will become virtually invisible to the human eye.
These rules apply when out hunting and have been posted as a guide from my military background. All these points help us understand how the animals react in the wild and how to hide from them in order to secure a one shot kill.