Resdesign an old, established website & domain requires careful attention to detail during the relaunch process.
The below video tutorial covers one of the biggest mistakes people make when redesigning a website, specifically, neglecting to add 301 redirects.
If your site structure has changed and your content has been moved, adding 301 redirects from old page URLs to the corresponding pages on the new site is essential. Making the mistake of not adding redirects can cause your page to drop in rank, and prevent visitors from accessing the content they were seeking.
For example, if someone finds a link to an old URL after performing a web search, they will be presented with an error message:

Instead, adding a 301 redirect notifies Google that the content has been moved, in addition to seamlessly redirecting the visitor to the right page. Other important steps include creating a sitemap, adding your site to Google Webmaster Tools and fixing any resulting high priority errors it identifies.
Redesigning a website can cause havoc on your rankings and harm the amount of traffic your site is getting, but it doesn’t have to. For the best results, always work with a website redesign expert
httpvh://www.youtube.com/watch?v=HjONLDhjqE8