Change the domain name
You may get into a point where you need to change the domain name of your website to a new one due a rebranding. You must ensure you have no other choice as this change is a major in terms of SEO and will have impact on your search engine rankings and losing traffic at least for a while is inevitable. To minimize the impact, you need to consider a few steps before redirecting your current website to the new domain name. The picture below represents the sudden traffic loss after changing the domain name:
Parked domain names
Probably your new domain name will be a parked domain and not in use, so you need to be careful with that. Never rush to dive into migrating your domain name, instead take your time and build up a few simple web pages, relevant to your existing one and upload it into your web server and point your new domain name in there. Wait for few weeks so when you type your domain name, it appears first item in the Google search results. If you have access to the pages linking to your current domain, you can change the links to the new domain in this period.
Redirecting web pages
At this step, start by redirecting your existing pages to the new domain. Matt Cuffs, the head of Google’s Webspam team suggests that moving pages individually rather than redirecting whole domain at once. This can be done easily by adding a 301 redirects in your .htaccess file, For example the following line will redirect a single page to your new domain:
redirect 301 /product.html http://www.newdomain.com/product.html
Or if you prefer to redirect each folder, you can use the following code which redirects whole product folder:
redirect 301 /product/ http://www.newdomain.com/product/
I suggest you to use canonical tag in your pages as well. This tells Google that where is the actual location of each page:
<link rel="canonical" href="http://www.gchat.com/" />
Check Google webmaster tools
Now keep an eye on Google webmaster tools, and be patient, It takes a couple of weeks for Google Bot to migrate your links from your old domain to the new domain. You will also notice that number of Indexes will start to reduce on your old domain and instead they will be increased in your new domain name. To make the process faster, you can use the Change website feature in the webmaster tools by selecting your new domain name from the list.