PLACING A PERSON in a scene doesn’t mean the person will look like they belong there. There’s always going to be the person in the foreground, with the landscape or room behind them. But there is a simple trick.
In the first image above, a man has been placed in this forest scene. But he doesn’t appear to be part of it.
Adding a new plant in front of him now places him within the background. The plant, though, is too obtrusive.
The answer is to blur the foreground object to the point where it’s barely discernible as a plant. But it has the desired effect: the man is now in the background, rather than on it.
You can see a video version of this, and other common Photoshop errors, here.