Wikidata has thousands of properties you may use to describe things. You are not expected to memorize all of the properties, but it can be overwhelming to know where to begin. A data model is the best way to know what properties to add to an item. If there is no data model, there are tools to see recommended properties.
One of these tools is called Recoin. To get started, we need to enable a gadget on Wikidata that will recommend how we can add to items. Follow this link to Wikidata's preferences page and scroll down to the gadget called Recoin. Click the box next to it, scroll down to the bottom of the page, and click "Save".
Make sure you are logged in to Wikidata to make these changes.