Using a Showcase Item as a templateEdit
Wikipedia has rating systems to evaluate articles. The best quality (and most well-known) designations are Featured Articles and Good Articles. Wikidata has Showcase items, which are items that are well-referenced, contain at least ten statements, have site links (a link to an item's corresponding Wikipedia page for example), and have labels in multiple languages.
Showcase items can be great templates to better understand how to build a high-quality Wikidata item.
Remember: Every item is unique. Having ten statements is a starting place. An item can have hundreds of statements. Similarly, some items can be very complete, but out of date. Others still can contain use the incorrect property (such as using the property "subclass of" instead of "instance of").
Remember: There are not many Showcase items, so this particular evaluation processes will not work for every item on Wikidata, but they should help you start to understand item quality.
Note: Wikipedia has a very well-documented process for article evaluation. Wikidata's process for Showcase items is much newer. Bookmark this link to see Showcase items.