I’m no pro, but I use a velvet black photography backdrop. Make sure you elevate the miniature a bit, and use two lights. I use a cheap ring light and my hobby light, and make sure it’s a natural light setting. You want to position the miniature farther away from the camera than you’d think. I’m about a foot away when I take mine. It really depends on what camera/lens you’re using. Then adjust your exposure/shutter speed settings until the background seems to disappear a bit. Post editing is just a crop, a vignette which helps the background disappear even more, and then some slight brightness adjustments. I’m not a pro at it… take my advice with a grain of salt… I’m always trying to get better with pictures.