One common element is the change in physical characteristics. The girl's human features are replaced by serpentine ones like scales, a long body, and a forked tongue. Another element could be the isolation that the girl - now serpent - might feel. She is no longer part of the human world and has to deal with being an outcast in a new form. Additionally, there's often a backstory related to why the transformation occurred, whether it was a punishment, a mistake, or something else entirely.
A girl to serpent transformation story could involve a magical curse. Maybe in a mythical forest, a girl disturbs an ancient magic and is slowly transformed into a serpent. Her skin starts to take on a scaly texture, and her body becomes long and sinuous.
Common elements often include a transformation process. Usually, there is some sort of trigger like a magic spell or a strange encounter. Another element is the physical changes such as growing ears, a tail, and having different senses. Also, there is often an adjustment period where the dog girl has to get used to her new form and abilities.
One common element is the psychological shift. The girl may start to think more like a boy, being more interested in typically male - focused hobbies or interests. Another is the change in social interactions. She might start to interact with others in a more 'masculine' way, being more direct or assertive. And of course, there's often the physical transformation in terms of appearance, from a feminine look to a more masculine one through things like different makeup or lack thereof, and different body language.
One common element is a change in appearance. The girl might cut her hair short, like many boys do. Another is the change in clothing style to more masculine ones such as wearing pants and shirts instead of dresses. Also, a shift in interests, like getting into sports or activities that are more male - dominated.
One common element could be the element of surprise or shock. Since laying eggs is not a normal human ability, the girl in the story would likely be very surprised by this new development. Another element might be discovery, as she tries to figure out why and how this is happening to her.
One common element is magic. Usually, there's some sort of magical object or being that causes the transformation, like a magic spell, a magic potion, or an enchanted place. Another is the change in perspective. Once the girl turns into an animal, she experiences the world in a new way, like different senses or abilities.
One common element is a trigger. It could be a magic spell, like in many stories where the girl reads an incantation from an old book or scroll. Another element is the physical transformation process. Usually, it starts with a tingling sensation or a strange energy coursing through the body. Also, the change in senses is common. The girl - turned - anthro wolf will often have enhanced sight, smell, and hearing.
One common plot element is the discovery of the slime girl. Maybe a character stumbles upon her in an unusual place like a deep forest or an abandoned laboratory. Another element could be the slime girl's transformation ability being a key factor in solving a problem or mystery in the story.
One common theme is the exploration of different forms of identity. When a girl transforms into a horse, there is a shift in how she perceives herself and how others perceive her.
Since we don't know the exact 'girl tf story', generally speaking, characters are important. There would be the girl herself, and perhaps other characters who are involved in her transformation, either as helpers or antagonists. The setting also matters. It could be a modern - day city, a magical land, or a post - apocalyptic world. And of course, the plot which involves the process of her transformation.