On editing any post on Stack Overflow, it shows me this message:

> 
> Your edit will be placed in a queue until it is peer reviewed.
> 
> 
> We welcome all constructive edits, but please make them substantial. Avoid trivial, tiny one-letter edits unless absolutely necessary.
> 
> 
> 

How can I decide if the post needs an edit and the edit is not trivial?

I mean, what are the key points should I remember while editing any post to make it substantial?