In my words, Rank of your keywords then firstly analysis your website. check on page optimization , titles , Google indexing, robot.txt and webmaster errors. After successfully submitted your site in webmaster then started link building techniques. You can use all techniques like forum posting, blog commenting, article , guest blogging and social media. in 15 days of time period you can see improvement in your website keywords...So please update your opinion and knowledge about that..
If SEO is like a wall that everything you writes in there would be fine, then your hypothesis can be right. On the contrary, SEO is an ever changing field with lots of updates occur rapidly. If you are about to aim for keyword ranking within 15 days, you will just find yourself cleaning the links you built from that period of time.
I would rather say that if you want to have a good reputation, then work for your domain authority. Because domain most of the time represents your brand. If your brand is widely known, then targeting keywords would be much easier than aiming for rankings alone.