Control the light and your background. Good lighting, preferably from two directions. Neutral background. Photo boxes are handy, and you can build them yourself.
Don't use the flash. Instead brace your camera well and use long shutter speed.
Your camera (phone) will surely have advanced photo settings. Find those, google how they work, test them.
Test, test, test. After an hour you will get it right, and then you have the right settings for as long as you use that camera.
Arrange your minis differently, find out the angle where they look best.
Take many photos and choose the best.
Check YouTube videos on the topic. You will find many, everything has a point. Watch several.
-Z