It is quite funny statement, As you have said that you wanted to increase the PR of your website from 1 to 4. The last update of the Google related to page rank was in 2014. I think, it is enough for your question. I would like to suggest you create some high quality links. This will help you increase the page and domain authority of your website.

Creating enticing content, generating quality back links and optimizing title tags can improve this website's PR.

Make sure that you honor search engine rules by following their rules, work on social media sites, blogs and forums.

How can you measure the PR because Google not showing it publically? So, focus on your work and do quality work to your website.

You should also include social media sites as well as blog websites, work on them as a real human being thus you can bring attention to your campaign.

PR of the website has been already removed by the Google a long ago. However if you want to increase traffic and visibility of your website, you can always work on best SEO practices.

It is important that you always follow the rules of the community and do not forget to work on niche with the same domain as yours.

-Unique SEO optimized content
-Use heading tags and Keywords
-Quality Backlinks
-Article directory submission
-Submit blog to Web directories
-Ask other blogger to link to you
-Improve User experience