Here's a website with a great collection of information that offers 'tufa and 'crete newbies solid foundational information we need to get us started in the right direction. Lots of good solid instruction, hints and tips and guidelines, and frequent updates with new techniques and ideas. And there's nothing for sale, so I can recommend it here without breaking any rules, (at least as I understand them).

Here is a link that might be useful: The Artistic Garden