Goya usually just signed "Goya" with simple and unadorned letters. He also had a longer, more decorative signature of "Fran. de Goya," in which the tail of the final a curls around several times.
Goya also signed some of his etching plates, but his editions were not hand signed.
If you want to determine if a Goya signature is authentic, please send a sharp closeup of it.