On the model specifically or the render in general? Also..some background on what's happening here? Is it school hours? After school? If for example it's supposed to be them breaking in to steal stuff and are arguing on how to cover their tracks..that's a really bad render.
Obviously it's not my example but if you want feedback on the scene, we'd need more information.
As it is, I assume it's school hours during a break or something. In that case, I'd add a few passing students (being alone in an empty hallway during a break between classes is weird). That's for the scene in general.
As for models, you really need to find better models for the lockers. Textures as well, but mostly models, or at the very least edit the one you have and add some bevels here.
View attachment 1312013
As for the girl, she looks creepy to me but I can't place it. Probably the eyes? I don't really know.
The general layout looks nice, but if I were you, this window shot is the perfect usecase for volumetric lights. Will look better and will fix the relative flat lighting, but will also take longer to render. So it's up to you really if you want to go that route.
Plus everything that
Techn0magier said. Some are easy to fix to get a good render, others are harder. He posted while I was writing so..no point writing them all over again. So I leave just the extra stuff I wrote.
