In fairness, that intro is all mixed up. The guy says that he is both 'an SEO expert' and 'I want to be an SEO expert' so, given that he's studying EEE at college/uni, I'm assuming the latter rather than the former. Whatever, it would still be useful to expand upon his own own ideas rather than just throw the questions out. Whaddya say Bivhab, what are your thoughts on website ranking?
The common "pillars" in SEO apply: keywords, content and links. Every SEO is going to tell you something different for their magic approach to mix them in order to achieve your desired result.
The other thing is to have useful SEO tools (to gauge good keywords, competition levels, content ideas, backlinks, etc). One of the most useful tools is Ahrefs (for backlinks, especially). SEMrush is also good (for ranking keywords). You also want to monitor backlinks (as they might be toxic to your site) and setup ranking reports for monitoring keyword positions in search results -- useful for before and after you start your SEO campaign.
So what's the most important part: action, I guess. Before that, a solid strategic plan, and constant optimization.