Don't worry all that much about Pagerank, Domain/Page authority is where it's at, and PR Updates take AGES to be implemented (Google only updates websites PageRanks every 6 months or so as of now) Contributing factors: Domain Age Linking Sites PR Juice Linking Patterns (This is going into algo level stuff that tends to be more about the way your backlink profile looks) Take a look at Tiered Link Building if you want to grow pagerank quicker.
I have come across with a website which has more backlinks like around 300+ but its page rank still in 1. So what should want to do to increase page rank?