1. When to use 

Use a dropdown select when there are more than 5 options. When there are less than 5 options, consider using checkboxes or radios for quicker scan-ability. ¹

2. Input Label

Include a clear and concise label that helps the user understand the purpose of the dropdown select. ³

3. Placeholder Text

Use placeholder text to indicate the type of information they will be providing. ²

4. Multi select count

Display the a count of the selected items if there are many choices. If there are only a few choices, display selection values in the form input. ²

5. Searchable Options

Include a search field if the list of options in extensive, such as a long list of line items names. ²

6. Selection Summary

For multi select choices, a selection summary may be used to display the selected choices below the dropdown select. This allows the user to quickly see or remove previous selections. Don't use a selection summary for single select choices.