You want visitors right? Make sure your content is optimized for a good search engine ranking, or Search Engine Optimization (SEO). Yoast SEO analyzes your posts and pages based on criteria that are important to search engines. For each post, you enter a Focus keyphrase that is the subject of your post. Based on the keyphrase, the plugin analyzes your post and comes up with recommendations. Each topic gets a score of green (good result), orange (improvement) and red (problem). The challenge is of course to get everything green, but that will not always be possible. At least make sure that the overall score of your post is green.
Besides analyzing your posts and pages, Yoast SEO does more. It creates a sitemap for search engines, you can configure how your titles will be generated and much more. The plugin is free but you can purchase a premium subscription to unlock more functionality.
Website: Yoast SEO plugin page
W3 Total Cache
A slow website performance is a reason for many visitors to leave quickly. WordPress uses a database in which content and configuration are stored. Especially if you use a lot of plugins, the performance can quickly decrease. With W3 Total Cache it's possible to drastically improve the performance of your website. It offers many possibilities to tune the performance, but I recommend that you try at least the following options:
Page Cache: this creates a static version of your page or post so it will not be build from the database each time.
There's a lot more to tune, but that requires some extra skills and understanding of performance concepts. With the three options I mentioned, the performance of your website will already drastically improve. This plugin also offers the possibility to upgrade to a paid subscription to get more features.
Website: W3 Total Cache plugin page
Large images can also slow down your website. Imagefy is a plugin that compresses your images so they will load faster. You can do this manually or automatically when uploading your images to WordPress. There are three compression levels: Normal, Aggressive and Ultra. I have set Aggressive as my default level. For each compression event, the statistics will be shown per image.
The compression of Imagify is very good and the loss of quality of the images is hardly visible. If you're not satisfied with the result, it's possible to restore the original image if you've enabled the backup option.
The free version allows you to compress up to 200mb of images every month. If you need more, you can purchase a paid subscription.
Website: Imagify plugin page
WebsiteDefender WordPress Security
There are many evil people outside. It's important to pay attention to the security of your website. A good best practice is to regularly update your WordPress setup, themes and plugins. You also have to make regularly backups, in case your hosting provider doesn't do that for you already.
To further tighten security, you can use WebsiteDefender WordPress Security. This automatically optimizes the configuration of your website so it becomes more difficult for evil people to damage your website. The plugin also provides recommendations for further improvements, but these require a little more knowledge of the underlying technology. With this plugin you can also make backups of your database, but not the files.