Thanks for the praise everybody
I don't use a shoebox (although that would be a good idea!). I typically use "heavyweight paper matte" by Epson, you can find it at Staples or any computer store for like $20 for a full pack. The pieces aren't as flimsy and you can stand characters up easily. It's just a matter of measuring the dimensions on paper, make sure it's scaled to your liking, and taping the actual stage together (although there are more reliable methods than using standard tape, it's just quicker for me to use). Also a hobby knife is required (or a standard razor) to make the characters more precise. I'll also try and make a tutorial soon!
Here's a quick one I did today. Can you guess what game it is??
I'm taking the pics using my cell, & the quality is horrible! I'll try and take better pics in the future using a normal camera cuz these low-quality pics really don't do the models justice ._.