One line = one buyable intention
The client should understand what they are paying for. “Supply and fit bathroom” can be enough if the detail is in an annex; otherwise split into measurable sub-lines.
Drop internal jargon
Abbreviations that help in the van do not always help a homeowner. Keep them for your own notes and prefer plain terms on the quote.
Reuse wording that already worked
When a formulation has been understood and accepted several times, save it in your catalogue. Consistency from one job to the next reassures.