Formal:
* Je rentre de l'école. (This is the most common and natural way to say it.)
* Je reviens de l'école. (This implies you were at school and are now back.)
Informal:
* J'arrive de l'école. (This is more literal and less common.)
* Je suis arrivé(e) de l'école. (This emphasizes that you have already arrived.)
Note: "L'école" is used when referring to the school as a place, while "école" is used when referring to the school as a concept.
Example:
* Je rentre de l'école, je suis fatigué(e). (I'm coming home from school, I'm tired.)
* Je reviens de l'école, j'ai appris beaucoup de choses aujourd'hui. (I'm back from school, I learned a lot today.)
The choice of expression will depend on the specific situation and the speaker's preference.