To the left you can see images of two templates in the template editor. As you can tell if you click on the image, one is far nicer to modify than the other. The difference is "TemplateData" - a way of storing information about templates, such as human-readable parameter names or a description, so that the VisualEditor can retrieve it.
One of the things we need volunteers to do is the adding of TemplateData to templates - particularly high-profile ones, such as infoboxes - so that they are easy to edit. You can read about how to structure TemplateData here.
You can probably think of some pretty important templates on your project very easily - experienced users know pretty well which templates are a big deal, and will inevitably find out when they try to use them and discover there isn't any TemplateData. However, we will also be building list of templates that are used the most, on a per-wiki basis. If your wiki does not have one, and you are interested in getting that data, please email okeyes-at-wikimedia-dot-org.