Shape. Your helmet, load bearing web equipment, rifle and other gear have a clear, often square shape, and there are no squares in nature. Break up straight lines with strips of burlap, camo cloth or netting in shades of brown and green. Elastic bands can be sewn to your uniform or equipment straps to facilitate adding camo strips or vegetation. Camo materials should not be attached to your rifle in areas where they may slip and interfere with your firm grip or the mechanical operation of the weapon. It is better to cover the weapon with paint or camouflage tape.
Shine. Most modern military equipment uses plastic or subdued painted metal fasteners and buckles. If the paint has worn off or you are using commercial equipment with shiny buckles, these need to be covered with paint or tape.
Other shiny surfaces that can reflect light include binoculars, compasses, watch crystals, plastic map covers and eyeglasses. Little can be done about eyeglasses other than using headgear with a low brim or mosquito netting, but other shiny equipment should be stowed away when not needed and used with caution. Shine also includes skin, even at night when it will reflect moonlight and flares.
Silhouette. Similar in many respects to shape, silhouette includes the outline of the human form and the equipment it is carrying. The shape of the head and shoulders of a man are unmistakable and a bare helmet attracts attention. The use of local vegetation as garnishing helps break up your silhouette. Thick handfuls of grass tucked into your shoulder straps are especially useful in breaking up the distinctive "head and shoulders" shape of the human figure and vegetation added to a helmet breaks the smooth curve of the top and the line of the brim. Take care not to overdo adding local vegetation. You shouldn't need a machete to hack a path through your camouflage to get at your ammo pouch or other necessary equipment. Also, a large bush or tree is sure to attract attention when it starts to move.
Silhouette also includes field craft. However well camouflaged you may be, it is little help if you "sky line" yourself by walking along the top of a hill or ridge line, or if you stand against a background of one solid color.
Smell. Even the most urbanized man will develop a good sense of smell after a few days in the open. He will be able to detect engine smells, cooking, body odors and washing. Some smells are hard to minimize. Soaps should be scent-free and activities such as cooking should be confined to daylight hours when other smells are stronger and the air warmer. Rubbish from cooking should be carried away from your operational area and buried only as a second choice. Buried objects are often dug up by animals and can give a good indication of the strength and composition of your patrol or unit as well as its morale. The discipline of refuse removal is important.
Sound. You can make a lot of noise while out on patrol. Your boots can squeak. Your cleaning kit or magazines can rattle in your ammo pouches. Heavy pack frames can creak.
Fittings on your weapon can rattle. Radios can have background noise. Coughing and talking can carry for long distances, especially at night. You must become familiar with a silent routine in which hand signals replace the spoken word and conversations are conducted in a whisper.
Proper stowage of your gear, taping of slings and other noisy equipment and a final shakedown before a patrol moves out will reduce noise. If digging a position, place sentries far enough out that they will spot an enemy before he hears the sound of digging.
Color. Though most modern combat uniforms are in a disruptive pattern camouflage, there may be times when this is less helpful. The trouble with camo clothing is that in the wrong environment, like cities, it stands out and says "Hey, look at me!" If fighting in built-up areas, a pattern of greys, browns and dull reds would be more useful than the typical woodland BDU pattern. Natural vegetation used to garnish helmets and equipment will fade and change color. Leaves will dry and curl up exposing pale under surfaces. You may have put dark green ferns and leaves into your helmet band while in the woods and then find yourself moving through an area of pale open grassland. Check and change your camouflage regularly. The most obvious color that needs camouflaging is that of human skin, and for that you need G.I. camo stick or, preferably, a commercial camo cream. G.I. camo sticks are issued in loam and light green for use in areas with green vegetation. A sand and light green stick is used in areas lacking green vegetation. A loam and white stick is for use in snow covered terrain. If camo sticks or creme are not available use burnt cork, bark or charcoal for the dark color and mud for the light color.
Dark colors are used to reduce the highlights formed by the nose, cheek bones, chin, ears and forehead. Lighter colors are used in areas of shadow under the eyes, nose and chin. When applying camo to your face it is useful to work with a buddy and help each other. G.I. camo sticks are rough on the skin and difficult to apply. A few drops of baby oil, skin lotion or insect repellent rubbed on the skin first will make it much easier to apply. Skin camo needs to be periodically touched-up as you move and sweat. A simple pattern for the face is to apply a light color first to the entire face and then add dark diagonal stripes. The diagonals cut though and break up the horizontal and vertical lines of the eyes nose and mouth.
Good camouflage is almost as important as good marksmanship. A well camouflaged man who is a poor shot will probably survive longer than the poorly concealed expert sniper.