Hi
I have three travel website, two of website hosting in Kuala Lumpur and one hosting in U.K.

Two website use Wordpress platform and one use Joomla platform. Two of website hosting in Kuala Lumpur is well ranked on Google for certain keyword.

My question is
1. What the best practice to link within three own website?
2. Should I use every article on website to link within website?
3. One of website based in U.K still new, should I wait Google index the website before I start link to others two website?

Thank you in advance.

Anuar