Its a very complicated subject one which is possible, but very dangerous. I'm not going to tell you how cause someone that asks this question should already know half of the answers.
But i will give you hints and if you have all of the knowledge of the words and know how to use them properly and not mess it up i will tell you.
EsaraMersaCursa (A type of lauguage basicly a strong magic toungue) fluently able to say the acient laugugae, Its the 3rd highest form of magic.
Destruction of the persons temple (body or soul)
A spell in the magic tounge to resurrect it (3 strongest magic possible) any other type of magic and you have sussecfully killed someone and will be hunted :)
When you soul or spirit leaves your body must return in 30min otherwise you body will begin disinegrateing (trust me the most painful thing every experienced, feels like your wrists are eating away at themselves)
Learn how to do astral projection 100% not half, master it.
Oww and if your a witch dont forget the saftey trap, you were born with massive pain and brings more pain then relief if you attempt everything. You also have to be strong enough to see them and destroy them and make sure the dont grow back..
Or their is a blood ritual that requires half of your blood 7.5L and its permanet for a mounth untill next moon, oww and it requires 10 special crystals.
Yer a few more things but your playing with fire and if you attempt any of these things your screwed and your going to be in a lot of pain.