What are some common ways of using CSAT?

Thumbs up, thumbs down

A simple thumbs up, thumbs down approach is good for getting high numbers to display to a board or on a website, but is not so good for further action or doing anything else.

Happy, neutral, sad

A 3-4 happy to sad face rating or including a simple "How did I do? Good, just okay, not good." with each email reply is best for rating the customer service representatives themselves and the experience of that particular support interaction. Being able to find ratings on specific replies rather than the entire experience is more helpful in reviewing how you are doing with your customer support responses. It also gives you a chance to up your game on the next response rather than the customer being sent a separate CSAT survey 24 hours later and then waiting to get their feedback.

1-5 or 1-10 score

Some use the Net Promoter Score (NPS) and CSAT interchangeably with a 1-5 or 1-10 score approach. This is best to evaluate the product and how good of a product you have, but isn't necessarily as useful for evaluating customer support representatives.