Let's say I have website A and website B in relevant niche. I want to provide backlink from website A to website B to increase SERP power. What things to avoid so Google wont know I own both websites? 1. We need to host each site in different web host, correct? 2. Do we need to protect domain privacy so they wont be able to see who own both sites or is it not necessary?
Different ip of your sites will be enough. But i do not know any cases that google penalty websites on the same ip )
if you have 2 good quality sites, with a related theme, you probably don't need to worry about being penalized by google for linking between them. having 2 sites that link together through relevant content is a totally normal webmaster thing to do if you have dozens / hundreds of sites then its a different situation