In my career as a VFX supervisor, I've helped supervise several miniature shoots. Shooting miniatures in substitution of a full size scene has been a common technique for almost as long as films have been produced.

There are several important steps to make the photograph convincing:

Use a small aperture

Consider a 1:10 scale model, and put your camera in the scene. Just look at it: that camera is massive! Instead of a 35mm film back, you all of a sudden have the same optics as a 350mm large format camera!

Because everything is so close to the lens, your depth of field will be much shallower. Compensate for this with a smaller aperture. This should scale linearly, so to achieve the look of f/2.0 on a 1:10 scale model, you'll need to use a f/20 aperture.

Add light

Because your aperture is smaller, you'll need correspondingly more light. Where aperture scales linearly, the surface area of that opening diminishes by the square, so you'll need 100x the light for 1:10 scale. Fortunately, this is still photography, so you can get plenty of help just from shutter speed. Otherwise, increase the physical light, or up the ISO.

Use a natural focal length

Some people suggest using a wide lens. While this has the effect of exaggerating perspective, overdoing it quickly makes it look like a miniature. If you want it to look natural, the field of view shouldn't be any different than how you'd shoot a full size scene.

Conversely, you shouldn't use an especially long lens either. This compresses the perspective, making the scene look flat and dull. It can also be a telltale sign of a miniature, since a long lens is a rough substitute for getting the camera in closer. Which brings me to...

Position your camera appropriately!

This is probably the single most important point I can make. If your camera is angled down on the scene, it'll look miniature. Angled up, it'll look larger than life. Position the camera where it naturally could — and would — be. If you take a photo of a building, chances are it'll be from the street, looking up at the building. If you photograph your miniature scene standing up, it'll look like you took it from a blimp.

In many cases, you'll need to carve out space for the camera. If you need the lens 1/2" above the floor, the body will stick many inches beneath the floor. Cut a hole or remove pieces to position it properly.

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Of course the scene itself may need improvement as well. The biggest giveaway is a lack of fine detail. In a full size scene, these come naturally, but in a miniature, it takes a lot of work to avoid a smooth, rounded appearance. One neat trick: for water, add some detergent to break up the surface tension. It gives it smaller wavelets.

Lastly, though admittedly off-topic for this site, if you're shooting video, your frame rate should be increased by the square root of the scale. So 1:10 scale would be around 3.1x frame rate (so instead of 24 fps, shoot 72). In this way anything affected by gravity will move at the right speed.