You have to realise that this is a transition from hard to soft - and then the soft (lime) over a long period of time eventually turns to hard. Each layer has its own personality, and you try not to create to many conflicts - otherwise - they part ways.

A godsend is 'concrete bonder' which is a flexible "Dr. Phil" moment to bond differing parties. The proper transposure is fresh lime modified concrete (with coarser aggregates), to fresh 100% pure lime plaster (with fine aggregates). Each of these materials has their own lawyer - and if you listen to them, and their exact demands, you will be up half the night trying to keep schedules. This is why lime plaster is dead in construction, but not barred to us in the arts.

Cement board is well cured concrete - the hardest material you can deal with, so its much more of a challenge to get things (lime plaster) to stick - but it can be done.

Steel mesh is another godsend to the world of fresco. Make something as thick as backer board with mesh. While it is still 'green' gradually increase coats with lime content, and smaller aggregate size. If you are really nervous - use concrete bonder between coats. This will result in a happy family that can't wait to gobble up your pigments into permanent, beautiful works of fresco.

The hardest part is to get started. The second hardest part is throwing away the works you don't like. Thats about it, really