Google Page rank is based on backlinks. Backlinks are Links pointing to your website from another website. The more back links you have the higher your PR will be. Apart from that also submit your sites to high PR directories.
For best results backlinks should be to relevant sites that themselves have PR. Google considers links from authoritative sites most important: ie. industry sites, organization sites, government sites, established educational sites, etc.
You need to find sites which relate to you theme and get them to link to you -however you need good content which tht sites users will find useful-
Dont bother trading links its worthless and a waste of time - plus too many black hat webmasters will cheat you out of the return link using methods you cannot spot.
How can I increase Gooooogle Page Rank 
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