Sounds like a competitive keyword, one of the best way you to get a reference is to check out those who are already ranking on top and see their site contents and structure and where their backlinks came from and try to do better than them...
There are 208,000,000 results returned in Google for that term, it will be competitive. Like the previous poster said, look at the sites ranked above you and determine how they got their rankings.
first check the key word competition.
Then after that do the basic link building.
But be sure your link is on page having good PR and also check the neighbor links do not submit the link on that page which has bad link.
I would suggest that you first try with another keyword, which has a lower competition especially if you are a begginer in SEO. After your site receives some traffic from that keyword, you can change it with a more competitive one.
You'll need to clarify what you are actually looking at. Is it the "exact" same URL that's having a different PR? It is highly unlikely as Google's PR changes all the time, but they only "push" a "snapshot" once every 2-4 months that is visible on the Google Toolbar. So, unless they did a push at that exact moment, you aren't witnessing accurate PR.
Now, what I have noticed is that sometimes when I visit a website, I will get one PR and then when I refresh the page it changes. This is because my Toolbar had a "chached" value that didn't get updated when I went from one site to another. What was left was the PR from the last page I was on at the previous site.
Ranking improve with link building not too much by SMO ,First of all site should be well optimized after that if you do make 30 link on relevant site and 2 article in 25 site and 20 forum then it automatically increase your site ranking.
Very competitive phrases...
Do not forget that such competition is the most popular open source CMS solution: Joomla, Drupal, Wordpres, etc...
Maybe you can arrive on the first page, but in such a competition you can not survive ...
I think perhaps the better option for some time that you pay Google to the listing on the front page ...
Perhaps a better option that one time you pay Google to the listing on the first page ...
My experience tells me that visitors do not like sponsored links, but will at least hear that you have it...
In the meantime, build links and journeys toward the top...
This is a very competitive keywords has high demand and supply. If you are going to optimize your website for this keyword then you need to put great efforts. You have to follow all SEO techniques including On page seo and Off page SEO.
On Page SEO includes -
1. Title tag optimization optimization.
2. Meta tag optimization optimization(Keywords and description).
3. heading tag optimization.
4. Content modification.
5. Image Alt tag optimization and Anchor text optimization.
Off Page SEO Includes.
1. Social bookmarking.
2. Directory submission.
3. Article writing.
4. Forum posting and blog commenting.
5. Press release
6. Ad Classified.