What is the best way to move site to new domain without losing google page rank
301 permanent redirect.
It is not full proof, but it is the best approach.
have a look at http://www.google.com/webmasters/ once you set your site up in there, they have a whole page of info about changing domain names,etc
You should also do a change of address after you've done your 301 redirects, so Google knows your intentions: https://support.google.com/webmasters/answer/83106?hl=en
The 301 redirects should be mapped page - to - page, so that the content on each indexed page is relevant to the content on the mapped page on the new domain.