Hey @Dmitry ?
In Outlook, I have a fixed template for replies to quote requests that I adjust based on the specific needs/requirements for a project, so as not to risk leaving anything unmentioned or unclarified.
I always specify that the amount relates to a specific service and, if extra services are involved, such as proofreading or file preparation, I specify that this will cost an extra XX. (I usually charge for file preparation unless it only takes 5 minutes or so)
I also specify the number of working days I need to complete the job and the deadline by which I need to receive confirmation and green light – otherwise, I'll need to confirm availability/feasibility again. This is in case they disappear after asking for that quote and then pop up again sometime later saying that's OK, while in the meantime I have accepted a ton of work from someone else ?
If the project is big and the deadline is some time ahead I also ask whether the translation needs to be delivered in one solution or in batches.
This must look like a lot to process to non-translation experts, which is why I leave it at that, but I'm sure there would be other things we need to clarify in quotes... which is why I'm looking forward to other answers ?