There are some algo like Penguin, Panda, Hummingbird and other Google Algorithms that can really make impact on Rankings of the site.
Link Building Strategy should be :1) All the links should be submitted Manually.2) All the back-links should be Unique and from Page Rank 2, 3,4, 5, 6+ top domains.3) All the links should be One way, Permanent, Approved,Do-follow and of high quality .4) All the links should be build Naturally & by implementing White Hat Link building only.
Also one important Factor is site should be Fully mobile optimized.
On-Site Activities should include :1.Optimization of Title Tags2.Optimization of Meta Description Tags3.Optimization of Meta Keywords Tags4.Header Tags Optimization5.URL Optimization6.Optimization of italics and bold tags7.Optimizing HTML Code etc
Off-Page SEO (Back-linking) should include1- Blog creation /setup2- Blog optimization3. Search Engine Submission4. Directory Submission5. Article Submission etc.