What do you need? A good reason if you ask me. Otherwise, they probably won't help.
Once you find your intent, create your statement of intent. A strong declaration of what you want, say it a hundred times over!! do you still want it?
Find a spirit among the 72 of the goetia that suits your needs. Use the sigil.
The way i did it was i drew the sigil of the spirit on a piece of paper, wrote my statement of intent, and a few other things and then burned it. I mixed the ashes into clay with appropriate objects. The clay was pressed and dried into a circular tablet, the sigil was traced upon it.
The newly created tablet was charged by making it the focus of evocation.