what is best way to forward WP-MU sub-domain to new domain?

Hi. I have a blog as a sub-site on a WP-MY installation.
I created a new dedicated domain.com for it.
So the current subdomain is:
http://armedia.al-rasid.com
New:
htt://armedia.com

What is the best, SEO-wise practice to follow, to guarantee all SEO is retained, and no access errors occur when following links of the old sub-domain?
I use Yoast WordPress SEO plugin, if that’s important.

ALSO:
What is best practice to do all the above, but have the redirect be not to armedia.com but to subdomain.armedia.com ??

Thank you