Make sure that your website is linked properly and that pages are working properly. A website without a proper flow within its available internal pages becomes a hindrance for search engine spiders to crawl the site effectively. This makes indexing your site very hard and thus puts you out of getting properly ranked. Unfortunately some of these pages do have valuable information that could be useful to the target audience.
It is always essential to get the right keywords and sentences on the tags, headers, meta description, images and on the body text etc. When doing so, it is a must to do a research on what your target audience are typing on the search engines to look for sites containing relevant information like yours. Example if they are searching for "How high is mount Everest," it is necessary to include that term on the relevant areas than merely mentioning "mount Everest" or "mount Everest elevation."
Include vital info surrounding and related to the search terms. Also it is much better to put the content on the body of a site in plain text than in image or PDF format since text format is better crawled by search engines than images.
Now this area is being strictly monitored by Google. Some webmasters do spend quality time on link building than on content. This later on becomes a spammy technique used to cheat search engines which in return makes them to take necessary action on your site. Websites are indexed and ranked by search engines according to the relevancy and the effectiveness of content. People search the internet for information. Link building for a website without concentrating on creating rich content is useless at the end of the day from a search engine's point of view as well as a surfer's.
What do you gain by visiting a site where the content is limited or outdated and without proper information the target audience desire? First make something compelling related to your target audience and then involve in online marketing such as PPC campaigns, social media sharing, blogging and other off-site activities like a paper news release etc, which could drive targeted traffic towards your site and in return creates a flow among your audience both in the online and offline worlds.
Usage of Webmaster Resources
Why do you guess search engines like Google and Bing have provided tools and videos etc to assist you regarding your website monitoring and maintenance? Most of them are free too. Search engines like Google are offering these free resources to educate the webmasters and related parties interested in the performance of their websites on vital facets that could affect their sites both positively and negatively. So without searching around for clues and guesses, make use of the guidelines and info shared on these resources to fine tune and maintain your website in an effective manner.