I found this (extremely long) care sheet online, and being no expert myself, I am interested to get your take on it (although I am not suggesting you read it all unless you have some time up your sleeve). About 1/3 of the way down it talks about substrates and recommends strongly against newspaper, along with some photo's of blue tongues with black feet. I would love to use newspaper, when I was a kid we used newspaper in the bottom of our mouse tank and it was so absorbent, do blue tongues need absorbent substrate? Have you used newspaper before successfully?