It's always a good idea to set your SEO Keywords, Descriptions, and page titles. These are key terms that search engines use to rank & find your site. In Duda, there are two places to set SEO keywords: Page Settings & Site settings. These are for page specific SEO terms & global site SEO terms, respectively. Here is an example of how to set the keywords, descriptions, and titles for your site.
Keywords are the terms that people search for while trying to find your site. The important part about keywords is that they match the content on the desktop site. Meaning that if you are running an oil change station, you should not have keywords relating to sushi. Here are the Keywords that CNN.com uses:
CNN,CNN news,CNN.com,CNN TV,news,news online,breaking news,U.S. news,world news,weather,business,CNN money,sports,politics,law,technology, entertainment,education,travel,health,special reports,autos,developing story,news video,CNN Intl
Notice that the keywords relate exactly to what CNN does. Also, they don't repeat CNN in every single keyword. CNN could have easily put CNN news travel, CNN news autos, etc.. but they know that repeating keywords is not a best-practice.
Description is what shows below your title on search engines. A good description is between 130 and 170 characters and tells an accurate description of what the website is about. As an example, here is the description that DudaMobile.com uses:
The fastest, easiest way to build a great looking mobile website in minutes. Includes hosting, site analytics, click-to-call, mobile maps and more
This description is 146 characters and accurately describes what DudaMobile does as a service.
The title tells users & search engines the page is about. Make sure titles are clear about what users should see on the page. This is one of the most important steps, as the title of the page is directly what shows up in search results on search engines. Also make sure not to repeat keywords over and over in titles, as this can be seen as trying to spoof results.
If you want to learn more about SEO best practices, check out this getting started guide released by Google.