Send a link, not a phone call
A quote given verbally has to be remembered, discussed at home and confirmed by another call. A link opens on the customer's phone, can be forwarded to whoever shares the decision, and has an accept button. The decision happens where the customer is, not when you can both find a minute.
Itemise by section
One number invites an argument about all of it. Labour, Parts, Tyres and Workshop charges as separate blocks let the customer see that the expensive part is the part, not you. Parts at recommended retail, labour as hours times a rate they can check.
Say what happens next
Four lines of terms on every quote — validity, deposit if any, what is included, what is not — beat a page of boilerplate nobody reads. Keep the standard service description on the line so 'I thought that included…' does not come up.
Follow up once, in writing
Two days of silence gets one follow-up: a short message with the link again. Automate it and it never feels awkward; do it by hand and it never happens.
Price the parts where the customer can see them
A customer who can look up a set of pads online will. Show the part at recommended retail with the labour beside it and there is nothing to argue about; hide the parts inside a lump sum and the whole quote looks padded. Your margin lives in the difference between cost and RRP, which the customer never sees — not in a number they cannot check.
Put the standard service description on the line, not just a name. “40,000 km log book service” becomes “engine oil and filter, cabin filter, brake inspection, fluids topped up, log book stamped”, and the question of what was included is answered before it is asked.
Approve extras while the car is up
Finding something else is normal. Stopping the job to chase the owner is not. Send the extra work as its own approval — a photo of the problem, the price, an accept button — and keep working on what was already approved. The extra lands on the invoice with the customer's yes on record.