If you are not an expert of Search Engine Optimization (SEO) it might frequently happen that you are not aware of important functions that are required to ensure basic SEO. And basic SEO is absolutely key, if you want to grow the visitors of your website with the help of search engines such as Google.
Without basic SEO, the pages of your website won't be displayed in the search results (in the worst case) or will be displayed much less frequently. And if they are displayed they might be clicked less, because the information provided in the search result is distorted, incomplete or unattractive.
In other cases you might loose track of what you have already installed and configured and what not. For both of the cases the Drupal module SEO checklist provides an excellent solution. It lists the most important tasks to be performed and modules to be installed. Thus you can step by step perform the required actions and keep track of the status.
You certainly don't have to install and configure everything suggested, but it gives you I kind of overview and orientation. On the other hand there are of course elements such the enabling of clean URLs and meta tags, which are an absolute must.