Make your Google Sheet structured like this sample Makeskill Spreadsheet, filling with your own intents, utterances, etc:
Check out the UX Guidelines. These templates should simulate how your actual cards will look on the two devices. The templates reflect what the Echo platform supports today. When designing the Echo cards, remember to design for voice first, and then augment it with cards.
After building the prototype through Makeskill CLI, then you can preview your cards through the Amazon Developer simulator or on your actual devices!
We have plenty of examples of varying complexity, from your Hello World to advanced.