I just started learning how to take pictures of clothing on a mannequin. I decided to take pictures against a wall in a shady area. The result is a flat image that doesn't show off form very well. Would appreciate tips on how to create more depth with images like this.
Firstly, by having your mannequin close to the wall, your camera has kept the mannequin in focus and the wall in focus. That is distracting. You can get the wall out of focus by bringing your mannequin away from the wall, then choosing a wide aperture (number around f/2, f/2.8, f/4) and focussing on the mannequin.
Secondly, the shaded location means that your mannequin is not producing many shadows. This is because the light in that location is diffuse - it is lighting your subject from all directions relatively equally. To create a shadow you need light to be stronger in one direction rather than another. To alleviate this, you could be tempted to go with sunlight, but that will cast a very strong shadow and that is usually not desireable either. My suggestion is to use a flash. To acheive this you could use a "speedlight" (which is the flash unit you plug in to the top of your camera) but put it on a tall tripod above and to the left or right of your mannequin. You will also need a remote trigger - this comes in a kit with two items: one will connect to the flash (that's on the tripod) and the other will plug into the top of your camera. When you fire your shot, the trigger will fire your flash. If you leave it at that, the flash will produce strong shadows. This is called shooting "bare head" with the flash. You could put a small portable softbox, designed for speedlights, on the flash. This will diffuse the light slightly and make the shadows gentler.
If you don't have budget or time to buy new gear, then consider shooting indoors instead, and have a large window to one side of your shoot. The window will spread diffuse light on your mannequin from the side. If direct sunlight is still creating shadows that are too strong, then hang a light white fabric over the window.
Photography is essentially a two dimensional rendering of a three dimensional subject. We use shadows to create an illusion of depth. The simplest way is to light the subject with what is called a main or key light. This light is generally high and off to the side. The main, thus casts shadows. These shadows are often harsh and due to the scale of our photographic media, the shadow areas are rendered too dark -- thus they can be void of detail. To mitigate we use a second lamp called a fill. The fill is subordinate to the main. Usually it is set half or quarter power as measured at the subject plane. We fill the shadows from the camera’s viewpoint. Thus the fill is located at about lens height and close to an imaginary line drawn – from camera lens to subject. Try two lamps of equal power. Place the main high and off to the side. Measure the distance main to subject. Multiply this distance by 1.4. This computes a fill to subject distance that delivers the fill light at 50% of the main. If this does not create the depth you seek, multiply main to subject distance by 2. This computes a fill to subject distance that delivers the fill light at 25% of the main. Try this method; it will create an illusion of depth.