Firstly ,after publishing website must be main constraint on On-page SEO here are:
1. Page Titles
2. Meta Descriptions
3. Meta Tags
4. URL Structure
5. Body Tags (H1, H2, H3, H4, etc.)
6. Keyword Density
7. Image SEO
8. Internal Linking
9. Create Sitemap and submit in google webmaster
10. Configure with AMP for mobile verson
11. Schema also implement for good visiblity at SERP
After that go heads for Off-Page Seo in Which use mostly these techniques are :
1. Blog posting
2. Article posting
3. Forum Posting as well as Question/Answer
4. Guest posting for earning great traffic and quality backlink as well.
5. Now new technique is using that is Skyscraper . this help to earn quality backlink as well as traffic also.
And also easy methods to get search engine rankings:
1. Target on the low competition keywords first (Make sure that your website has a good score – Bounce rate, Loading time, Mobile responsive, User-friendly).
2. Low competition keywords are an easy way to reach the top of the page if your website has a good score.
3. Focus on Local SEO part.
4. Once you reached the 1st page of the search engine. You will get traffic to your website and trust flow from the search engine.
5. Now you focus on the highly competitive keywords.
Have a Nice Day !