Access to
standard written forms would help many who are good at the practical tiling side of things but lack confidence in documentation. eg. standard terms of business, terms of payment, clauses that should be included in quotations etc.
A way of registering work completed that would record eg materials used, methods used etc. that could be part of some type of guarantee for the work (customer payment premium). If you want double glazing fitted now it has to be by a member of FENSA so that you have some form of guarantee - so maybe something similar to this. I think similar things apply to tiling in other countries.
It would have to be meaningful to the customers of members. Members must be vetted for their ability to do just general tiling work, plus design and fitting wet-rooms, plus under tile heating etc. or whatever they will be claiming they can do as members. Members must be seen as more than someone just paying to be a member (there are too many of those associations already).