Thanks!
Looking at my score I can see improvement, too :)
I've learned a few things on my first steps: - never start with small things when viewing the image at 200-300% (nobody can recognize your small things at 100% and you easily get bored drawing that way) rather start with some big thing and add details later
- try to make your objects look 3d with shadows and a lighter and darker side
- add flaws to your objects (sounds stupid, doesn't it? :) I mean those little cracks or dirt, makes your objects look more realistic (only if that is what you want to archieve, of course)
- and of course blend well!! try to guess the object your neighbor wanted to draw and finish it!!
I don't want to say that I did incoperate these things in my image well, (the box for example could use a few more flaws and it looks like it is floating over the ground :) these are just my 2 cents on tiling :) (btw. correct me if you have different opinions on these tips)

Working "general to specific" usually makes all your drawing better.

thanks for sharing! :P I'll use your suggestions in my next tile.. hehe