Increasing seo score is just like creating backlinks for increasing pagerank. But here the seo score is based on the quality of the background used in the site, which includes the design of the site, loading time of the site and number of contents in it. Loading time of a site is an important thing for the increase of both seo score and pagerank. This is because google always give more attention to the fast loading site that the reason why seo experts are telling that using of iframe and pop under are harmful for a site. Another important thing is the quality of the content, more a site having content has more chance to appear in the search results. So adding contents of trend keywords are very useful for a site rather than going with images and videos. Another important thing which attract the visitors is the design of the site , google gave seo score based on the design also. Using of labels and separate pages will provide more chance to increase seo score. Google give pagerank and seo rank based on the trust that they found from the service of the site. Usually scam sites starts for only some periods, cheat others or make some cash and shut down, which is not accepting case for google . So for that google be careful to make trust of the site before giving pagerank and increase seo rank.
For that age of a site will help to determine the faith of the site so old site has more chance to increase its seo score. Seo score and pagerank will help a site to come infront of the search results so that it will get more visitors. Quality backlinks will help to increase the pagerank while the contents and other factors will help the site to increase its seo rank. So the main focus of a webmaster is to make faith in the eyes of the google. So that they can improve the site ranks. All the best.