What is the correct way to transfer sites from one domain to another?
 

I have 2 domains that are similar in nature.

I rather stupidly, put a bunch of content on domain1.com that after it getting listed in the search engines, realized would be MUCH better suited to domain2.com.

What is the appropriate method of moving all of the content from domain1.com over to domain2.com without being penalized by the search engines?

Should I just copy it across and delete it from the original domain1.com or redirect with .htaccess, etc? :helpme

I should also mention that in a few months time, I want to be able to develop domain1.com into a different type of web property with a similar theme, if that has any bearing on how to do things?

1. 301 redirect domain1 to domain2 page-to-page.
2. Confirm change of address in GSC.

Just move it or just have the html with full path to content.

Redirecting properly and making sure that you don't have duplicate or internally competing content. Make sure that you have a proper hosting for that too.