Yoast SEO – This plugin will help you to create better posts/pages. It will give you a overall SEO score of your written content, it will analyze your content for keywords and make suggestions on what you can do to create a more search engine friendly website overall. It also provides the ability to create XML Sitemaps and much more.
W3 Total Cache – This plugin will help you to improve your sites speed and user experience. I would recommend using the default setting if your just getting started until your confident you now how to tweak the setting to your liking.