Short answer: crawl the existing site first, preserve valuable URLs, map every changed URL to one relevant destination, carry over useful content and metadata, then validate the live site immediately after launch.
Before design begins
- Export indexable URLs, titles, descriptions and headings.
- Identify pages earning organic traffic, links and conversions.
- Record canonical tags, structured data and internal links.
- Benchmark Core Web Vitals and conversion events.
Create a URL preservation map
For each current URL, decide whether it stays, changes or is removed. Avoid changing URLs for style or organizational preference alone. When a change is necessary, use one permanent redirect to the closest relevant page.
Protect content and search intent
A beautiful new page can still perform worse if it removes the specific information that satisfied search intent. Improve clarity and structure, but preserve useful topics, evidence, answers and internal relationships.
Launch checks
Test redirects, canonicals, robots rules, sitemap output, analytics, forms, structured data and mobile rendering. Monitor crawl errors, impressions, clicks and indexed URLs during the first month.