Tell me what you are building. Every quote is fixed and agreed in writing before any work starts, and the conversation costs nothing.
Fill in what you know. Anything missing, I will ask about when I reply.
Your web address if you have one, roughly how many pages you think you need, whether you are taking payments or bookings, and what the site has to achieve — more calls, more orders, fewer questions on the phone. If you do not know yet, say so; working that out is part of the job.
Two things here answer most of a first email on their own, and neither asks for your address: the website cost calculator for a realistic budget range, and the free website audit if you already have a site and want to know whether it is worth repairing or replacing. There is also how I work, pricing and the FAQ.