3. Not Putting Title And Description Tags on Pages.
Have you ever visited a web page that showed the words "new page" or "Untitled Page" at the top of the browser tab? The website owner forgot to put a title tag on the page. The title tag, which is in the head section of the document is treated by search engines as one of the most important indicators about the content of a webpage. If you leave out the title tag or don't pay much importance to what you put up there, then you are wasting a good opportunity for optimization , as well as showing a sloppy kind of site construction.
Similarly, the description tag is often shown in search engine results pages (SERPS) as the description of your site. If you make a compelling description, it helps people to click through to your site. Ideally you want your site to be well ranked, but a high ranking is not enough. You need people to click through once they see your site's listing, and a good description can help you out.
4. Putting the Same Title and Description Tags on all the Pages.
Each of your pages is unique and has a special function, and you should let search engines and users know about this by changing the title and description tags to match the content on that particular page. It is not possible to optimize one single page for many different search terms, but it is possible to optimize each of the pages of your site for one or two important search phrases. If you take the time to make unique title and description tags for each of your pages, you can take advantage of this possibility and rank well for several search terms.