Always "waste" time studying your calls.

Before even going in on coding, you should first learn what it is that is being asked of your code.
When you do this, you will have a bigger picture of what it is that is being required of you.
For example, I'm currently undergoing a project that fundamentally is going to update the whole company internal system in order to have it working correctly, as the current version is legacy code, there isn't much to update, instead of creating a-new.

This means we need to learn how the whole system works and operates so nothing is left out. and as a bonus, you will already have a picture of how it could become and maybe even implemented in a new better easier way to use and maintain.

Also, Clean-Code is best. 'nuff said.