Use Card as the main container for your content
Because of its white background, it will highlight your content against gray-ish background.
Don't use description for any important explanation
Be careful about description, users tend to skip it. If you need to tell something really important, it's recommended to use Informational Alert.
Card with sections
Card sections allow you to create separate sections in every card when you need to create more advanced content structure.
Use card sections when you have more types of content in one card
It can be great to use it in Passenger card when you need to split form with personal information from baggage or insurance section.