Familiar is a word that starts gaining popularity among new comers in witchery and the paranormal. The popularization of the word comes from pop culture but it has a quite ancient meaning.
Familiars, What Are They?
You may have heard of the term “familiar spirits” in paranormal shows like The Chilling Adventures of Sabrina or Supernatural, but this word is also mentioned nine times in The Bible. The first mention of this phrase is found in Leviticus 19:31:
“Regard not them that have familiar spirits, neither seek after wizards, to be defiled by them: I am the LORD your God.”
King James’ Bible

God’s people were not to consult with mediums or fortunetellers. Leviticus 20:6 notes God’s opposition to involvement with people who communicate with evil or familiar spirits:
“And the soul that turneth after such as have familiar spirits, and after wizards, to go a whoring after them, I will even set my face against that soul and will cut him off from among his people.”
King James’ Bible
The Definition Of A Familiar Spirit
In Western demonology, Familiar, a small animal or imp kept as a witch’s attendant, given to her by the devil or inherited from another witch.
A familiar spirit, i.e., alter ego, doppelgänger, personal demon, personal totem, spirit companion, is an individual’s double, the alter-ego. It does not look like the individual is concerned. Even though it may have an independent life, it remains closely linked to the individual. The familiar spirit can be an animal (animal companion).
Pierre A. Giffard

The familiar was a low-ranking demon that assumed any animal shape, such as a toad, dog, insect, or black cat. Sometimes the familiar was described as a grotesque creature of fantasy, an amalgam of several animals.
“The definition of a familiar may vary from person to person. Some believe that the familiar is a projection of the self, others that it is a separate entity, and still others that it is a physical animal.”
Wikipedia
How Do I Get A Familiar?
Today’s modern Wicca does not talk about the animal companion type based on Ole’s British lore. Today’s familiars are more spiritual; the modern witch sees it this way, with which the individual feels an affinity too.

These are not the cute cats that watch over-friendly good witches like us on TV. These familiars are rooted in another plane. You could say others also believe that demons come from another plane of existence.
These familiars/animals are not necessarily evil; they’re far from being just a household pet and are treated as partners in the practice of magic.
But What Is The Definition?
“The definition of a familiar may vary from person to person. Some believe that the familiar is a projection of the self, others that it is a separate entity, and still others that it is a physical animal.”
Wikipedia
Is there a way to bring a familiar forth? Yes. One way to do so is to call upon a demon who will help achieve such a manifestation since they have extraordinary powers and control such entities. Several demons can help with it.

The one demon I believe is most helpful in this matter is the Goetia demon Buer.
Buer is a great president and is seen in this sign; he absolutely teacheth philosophy moral and natural, and logic, and the virtue of herbs: he giveth the best familiars, he can heal all diseases, especially of men, and reigneth over fifty legions.
Pseudomonarchia daemonum – Johann Wier (1583)
It is an exciting concept to think that actual familiars and demons may come from another plane of reality.
So What Is The Plan For Getting A Familiar?
1. Decide on the familiars’ name: This makes it easier to call upon the familiar. A name that will remind you of its purpose can be helpful. As long as the word means something to you, you can use any character, even codes.
2. Assign the familiar a sigil: You may create a new sigil based on the purpose for the familiar, or perhaps you want to link the demons sigil to the familiar at the point of creation.
3. Provide an object for the familiar to reside within: A voodoo doll, a fixed object, or something live. You will be “feeding” this object so ensure you can get to it when needed.
4. The “Awakening” Ritual: You could do this ritual on the astral plane or the same way you do your current ritual openings.

5. As long as you include the following elements in your opening, you can use any opening ritual method you usually use.
6. Repeat after seven days: Repeat the above, and offer the familiar what you feel is asking for.
7. Assignment of the task.
8. Lastly, make sure to call back you’re familiar after its assignment and love it.
9. Should the familiar not complete its tasks, ensure you follow through with the punishment, as stated in your charging ritual. Destroy the familiar. Some people will choose to banish their familiar after the task is complete.
If You Go Down That Path
If you decide to do this, ensure you thank the spirit for working with you and thank your demon. There is nothing worse than a spiritually weak witch fearful of destruction and the possible consequential retaliation.

As with old legends and stories, familiars, demons, and witchcraft are other mythologies and religions. Practicing in any of these requires due diligence and practice. These are some of the steps to follow, so please read up on this.