I do not know how to describe a Skinwalker to you other than it is a Native American or specifically Navajo Witch Doctors who has become corrupt and rather than healing and giving wisdom they haunt and curse those who fear them. Some say they can even possess you if you make direct eye contact. They feed off of fear and can become almost any animal. Though it is said they can only impersonate animals they have killed and skinned. Through these pelts and skins they are able to disguise themselves as these animals. Once they become these Skinwalkers they naturally do not look human anymore. They will always have some animal like patches and will be more hairy, larger, lanky, and feel no empathy. They have significant speed and strength. They however cannot travel onto Sacred or Holy lands of Native Americans or Religions (Example: Church, Native American burial grounds). They enjoy toying with prey, become power hungry, and can even disguise their voices and disguise themselves as people they have skinned. They will only skin you if you show fear, and come in direct contact with them.  Nobody is really sure what happens after you have a fearful 
							encounter with a Skinwalker. But more than likely it 
							will not kill you. They will probably stalk you, 
							torment you, and try to instill as much fear in you 
							as possible to empower them. The more you fear them 
							the more bold they will become in trying to take 
							your skin. Whether they take your skin while you are 
							dead or alive is debatable. Whether you live or die 
							from the experience? It's hopeful that you are dead 
							by the time they are done. Maybe they don't want 
							your skin? What happens then? It is likely they will 
							want your skin but if for some reason they don't 
							they will tear you into small strips of flesh and 
							either consume or decorate their home with your 
							remains and use your bones for tools and ornaments/ 
							accessories for their person. Skinwalkers cannot 
							enter homes without permission and can make any 
							animal noise or the general distress noise given off 
							by a person from adult to infantile ages. They can 
							be spotted in animal or human for as stiff, and 
							unnatural, and when they are in any disguise they 
							are unable to express facial emotions. 
							that you know what a Skinwalker is and you still 
							want to become one allow me to explain the ritual. 
							There are two ways to perform the ritual. The easy 
							way is EXCLUSIVE to those who have Navajo blood 
							running through their veins or are strong 
							descendants of a Native American tribe in relation 
							to the Navajo. If you have very little to no Native 
							American heritage in relation to the Navajo then it 
							becomes a bit more complicated but do not worry you 
							are not excluded from being able to perform the 
							ritual. I 
							shall first explain the easiest way to become a 
							Skinwalker. AGAIN this ritual is exclusive to the 
							Navajo and if you are to attempt this ritual without 
							a noticeable percentage of Native American blood 
							running through you then you have left yourself open 
							to being possessed by a Skinwalker and your 
							bloodline to be haunted and tormented by 
							Skinwalkers. If you want this to happen or not is up 
							to you.  To 
							begin the ritual you must carve yourself a totem 
							with some resemblance to the animal you believe to 
							be your spirit guide, a inheritance from your Native 
							bloodline (Necklace, beaded bracelet, tool, et. 
							passed down by Native relative), a kilo of St. Johns 
							Wort (can be replaced with Rosemary or Garlic), and 
							an animal skin (preferably fresh),a traditional 
							blade (not plastic handles), and a blood offering 
							(yes your own blood).

                                   
After you have collected these these materials you are prepared for the ritual.
The first thing you must do is go to a place that is natural (no cities, suburbs, town, neighborhoods, concrete et.). Find an empty spot with nothing more than grass and small vegetation. Form the best you can a symbol that represents your family bloodline with the herb you have chosen and place a single whole piece of the herb in the center of the symbol. Next take your inheritance item and place it around the single herb in the center. Place the totem you have carved just North of the herb in the center and then use the knife to draw blood from your body and complete the outline of the symbol. Take the knife and stab it through the herb in the center and then put the animal pelt/skin over your back (or over your head) and stand just south of the symbol. 
Now that you have created the symbol you may now kneel and chant the words (in native tongue)
"I am (state your name) and I wish to become one with my spirit. I give you my families possession, my mind, My body, and spirit. I ask for the knowledge of the great Witch Doctors and Shaman, please. Grant me the power of a skin walker". You must chant this between three to five times. Bring a paper with the words written on it if you must. If you don't speak the chant properly then nothing shall happen. If you do not speak the chant in native tongue you leave yourself open for possession, if you have not brought all necessities you endanger your family and leave them vulnerable to curse. 
If you have done the ritual properly then your spirit guide will appear before you. No matter how enlightened you think the creature to be or how pure you see it the one that shows before you will be solid black with no descriptive features. This spirit will now merge with you and your body will begin a half transition between you and your spirit animal. When I say this it is by no exaggeration, this is going to hurt a lot. Every change and morph within your body you will feel with explicit detail. If you have failed to bring or perform any part of the ritual and your spirit guide has appeared you have made a terrible mistake and you will now be clawed, bitten, crushed, stabbed, ripped apart and consumed by the very creature you thought to have been your spirit guide. 
Once you have completed the ritual correctly and the transition is complete congratulations you are now a skin walker and all witch doctor magic, spells, knowledge et. Are all inclusive. 
Before attempting this know that there are no redoes, take backs, refunds, rewinds, undoings. All decisions are final. Not that you would be capable of regret but whatever is human within you now will be gone. Perform the ritual with caution. 
Now if you have none to little Navajo blood or heritage you are in luck. There is a ritual for it however it is a bit more complex since native traditions are not so "welcoming" to outsiders which goes for the spirits as well. Good or bad. The end result is the same as if you were Navajo so don't worry you won't get a short end of the deal just for your heritage. But there will be a process in proving how dedicated you are to becoming this Skinwalker. So let's begin.
You will need a small totem of Native American descent, you will need a trinket crafted by a Native American, a kilo of one of the herbs mentioned or other that are native to North America, an animal skin (must be fresh), a knife with a handle crafted from the remains of an animal (Example: Deer handle knife), you will need your own blood as well as the blood of a Navajo (about one liter will do), and a bone from the Skeletal remains of a Navajo. 
You know when people speak of misfortune coming to those who desecrate Native burial grounds? Well you have twelve hours to complete the ritual after taking this bone. Failure to complete the ritual in time with either leave you cursed until you return the bone, or if your time runs out and you do the ritual anyway there will be a fate worse than death awaiting you. They will take you and you will not be allowed to die. "Fate worse than death" is an understatement. Your spirit will belong to them and it is of course unknown what happens when you are taken because nobody has been there and left, found a way to arrive without being stuck there, or even attempted. 
The ritual itself is exactly the same as the first except the symbol you will be creating will be the native symbol of "acceptance". This will show you are willing to take on the traditions of native culture as well as accept these dark spirits with you. When you chant the words you must speak them in YOUR native tongue. Failure to comply will result in angering the spirits you summon and they will either resent you or curse your bloodline. As for the bone as you chant you must hold this over the symbol the entire time as part of your offering.  All failures have similar results to the first ritual. 
Now that you are a Skinwalker enjoy it while you can. For the more you take, the less you have, the less you are, and the more it that emerges from your most animalistic desires.