Right, 301 redirection would be the only effective choice when you want to keep SEO juices from the old domain. Have a nice day,
Thanks for your reply! If I set preferred domain in google webmaster tools but haven't set permanent redirect, what will happen?
If you haven't set the permanent redirect Google webmaster will still index the old domain. And if ever you already set the permanent redirect make sure to add the new site on webmaster tools so that Google can crawl all details of your site.