becoming an animagus

“The process is extremely difficult and can result in disaster (such as permanent half-human, half-animal mutations) if done incorrectly. 

A witch or wizard must keep a single mandrake leaf in their mouth for an entire month (from full moon to full moon). If the leaf is removed or swallowed, the witch or wizard will have to start over again. 

At the next visible full moon (if the night happens to be cloudy one will have to start all over) the wizard must spit the leaf in a phial within range of the moon’s pure rays. 

To the moon-struck phial, the wizard or witch must add one of their own hairs, a silver teaspoon of dew that has not seen sunlight or been touched by human feet for seven days, and the chrysalis of a Death’s-head Hawk Moth. 

The mixture must be put in a quiet, dark place and be in any way disturbed. The next thing that must happen is for the wizard to wait for an electrical storm, whenever that might be. During this waiting period the wizard must, at sunrise and sundown without fail, chant the incantation ‘Amato Animo Animato Animagus’ with the tip of their wand placed over the heart. 

When, at last, there is a lightning storm, the wizard ought to move immediately to a large and secure place, recite the incantation one final time, and then drink the potion.”

-Pottermore Presents: Short Stories from Hogwarts of Heroism, Hardship and Dangerous Hobbies, Chapter 1 (Minerva McGonagall)

So THAT'S what the process is. I suppose it could be easy to keep it a secret past the Mandrake issue (can't they just hide it under their tongue though? How big are Mandrake leaves?)