Lunar, it would be very difficult to just spill years' worth of study specifically on familiars in a single post -- especially without knowing your exact tradition.
Whether you believe a familiar is called, created, or comes on its own, how yoiu 'acquire' one may be different.
Which tradition you follow will also have a very strong impact on your approach to familiar spirits.
So just telling you what to do since you want a familiar is basically fruitless. You need to invest the time and effort in study and practice.