I would make troubleshooting for the issues. Firstly, I would designate whether it is a new project. Again I will analyze relevant keywords and phrase for the site I am optimizing for as well as took an insight study of competitive analysis. If the website and pages has been index and appears in the first 10 pages of search engine result page but not in the top three, I would go for some transformation to on page text, page titles and page descriptions. But in the case if website has not been indexed still or dropped from index, might be it comprises some big issues and total re-submission and re-work might be required.
However, I opined here that this post will be highly beneficial for who are stepping towards marshaling their career as SEO professional especially for those who are still freshers. Moreover, in this post I have also listed some useful SEO interview question for experienced professionals that will definitely help them to grab their dream job and offer a great opportunity to add sparkles in their career.