ServiceNow is a powerful IT Service Management platform, but it is also a very "open" platform. There's little you can't do, with ServiceNow. But with this great development power, comes great development responsibility - and risk. This is what best practices, and your development instance, are for. By looking for best practice advice from industry pros on ServiceNow community posts, blogs, and articles online - and by trying out new techniques on your development instance first - you can be more confident in your ServiceNow development and administration decisions.
As you learn more about the platform and how it works, these best-practices will become intuitive and second-nature to you. Keep reading, researching, and learning, and soon you'll be writing technical best practice documentation of your own.