@diego_biosteam I think what @Lee-White meant was to make every effort to present a clean and polished illustration (by good scanning, cleaning it up in Photoshop, cropping it properly, etc), not necessarily embellishing it with borders, etc. If you look at the example he used, it was poorly lit when photographed, and had a hand-written, torn note to ID the creator.
As for feedback, your lighting is too even across the illustration. Things need to get a bit darker the farther down you go in the picture, even if there are other lights on that bottom floor. And I would add a few more characters to the scene to give more life, interest, and action.
If you do some research on character design, you will find many people talking about a character's silhouette—making the character's action recognizable even if the character was filled in with black. One way I read was that "a successful character should be recognizable by their silhouette alone". Consider adjusting her hands a bit so they are outside of her body frame, and maybe add a few more details to her outfit that would make her unique in the world she lives in. And you need to work on making her look more scared of the heights—have her further back on the platform, maybe leaning back some; maybe she is off balance.
Lastly, the background needs more than just an orange gradient. Make it look like an elevator shaft with pipes, panels, lights (think Death Star).