I'm kind of working on my own game right now but will gladly give you some tips on how to make a demo to maybe attract more people.
1. Rendering images
Rendering images isn't that difficult.There are a lot of great programs out there are relatively easy to use (heck, I figured them out.) One of them is poser. There is a huge downside to poser, it costs A LOT. That's why the main one people use is Daz. Daz is a brilliant program and most importantly, IT'S FREE!
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There are tons of tutorials out there and once you get the basics, you can pretty much figure the rest out for yourself really easily. The only problem is rendering the images can take some time if you don't have a decent CPU. To significantly reduce them, turn OFF rendering quality (unless you have a good CPU) and you should be on your way to making a demo.
2.
Getting products for your renders
There are lots of great sites out there that give you free stuff. The top one I would suggest is Renderosity.
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One tip though, make sure that you're getting things that are compatible with the version you are using.
3. Coding your game
Possibly the easiest program to use is ren'py. That's what a lot of the big games are made with. It's really simple (although some things are extremely complex.) There are lots of tutorials out there for this too and the basics are easy enough to get to grips with.
If you decide to try and make a demo and get stuck on something, let me know and I'll try my best to help you.