I do a lot of photographing of small scale miniatures (I've also been working on a 6mm American Revolution project, and do lots of 1:1200 ships) and I use a Nikon DSLR with just the basic 18-55mm lens that came with it. Nothing fancy.
I agree with a number of the comments already given here. A cheap tripod is a big help. I paid less than 30 dollars for mine. It's not good for field shoots, but for photographing things sitting on my desk it's just fine.
If you don't want to use a tripod (still recommend you do), you will need to be using a faster shutter speed (so the image doesn't blur) which makes even stronger light all the more important. I have two swing arm lamps on my desk, one of them with a halogen bulb for extremely bright light (watch out, it gets very hot so don't leave it turned on too long). I position the normal bulb close above the subject, and position the halogen lamp in front, low down.
I'm not crazy about light boxes. They can be done right, but often aren't, and so often lead to the figures looking back-lit. I just use a piece of construction paper propped up against a box in a curved position as a backdrop. I like the mat you're using, it looks good to me.
If you want to improve your depth of field, set your camera to allow you to adjust the aperture, while the camera itself adjusts the rest (unless you really want full manual. Great to have more control, you just have to think about more factors). Setting a higher aperture number will narrow the diaphragm and increase your depth of field, but again will require that you use stronger light. I completely agree with the above advice that you avoid using the camera's built in flash. It almost always looks bad.
Another thing using bright light will allow you to do is set a low ISO number – this is basically how sensitive the photo plate is. An ISO 0f 200 will give you a lot of detail, and look better when you crop an image and blow it up.
Also remember to set your white balance for the type of bulb you're using – incandescent or fluorescent (unless you're filming only in sunlight, in which case use that option).
jwhitegallery.blogspot.com
6mm Adler American cavalry (3rd Continental Dragoons)
Here is a 1:1200 GHQ ship model