To quote a job you have never done, research how it is done, break it into tasks you can estimate, add a contingency for the unknowns and be clear about assumptions. If the job is outside your skill, licensing or insurance, decline or refer it.
Step 1: Research first
Watch manufacturer instructions and trade tutorials, and ask a supplier or experienced tradesperson. Do this before giving a number.
Step 2: Break it into known pieces
Most jobs include demolition, prep, installation, finishing and cleanup. Estimate each separately using work you have done.
Step 3: Price the risk
Add a contingency line for unknowns, or state a range with the conditions that would change it. Put assumptions in writing. See writing a quote.
Step 4: Know when to say no
Decline if the work requires a license you lack, is unsafe or exceeds your insurance. Refer a trusted pro; that earns goodwill. See referral network.
Step 5: Record actual time
After the job, compare estimate to actual and save notes. See time tracking.
FAQ
How do I price a job I have not done before?
Break it into smaller tasks you can estimate, research the process and add a contingency for unknowns.
Should I tell the customer I am unfamiliar?
Be honest about what you can deliver. Saying you will research and quote carefully is fine.
What if the job is outside my license?
Do not take it. Refer it to a licensed professional.
Should I quote a range?
A range with stated conditions can work, but a fixed price with assumptions is clearer.