To increase the page rank you need to focus more on offpage optimization of your website. You have to perform natural and relevant link building. Use link building techniques like article submission, search engine submission, social bookmarking submission, local listing, forum posting, guest blogging etc. The more you get backlinks from standard and reputed websites you will notice a growth in your page rank. This process is a long term so if you are looking for increasing your page rank in a month or two, than it is not achievable. So keep patience and try to build relevant links.