Don’t Just Pick up and Move
If you have an existing website that has been around for a while, you want to be careful not to lose any SEO value or traction gained for pages that Google may already have indexed.
All too often web design companies are so anxious to get the opportunity to build your new website that they overlook one key fact.
Changing your domain name or your existing URL structure means you will essentially be starting from scratch.
Without a plan and proper implementation you will lose all of the existing back links to your site and increase the chance that Google will now see those index pages as dead links.
Be very careful that the person or company who is developing your new site understands the techniques and process of effectively migrating to a new domain or URL structure.