write comment it's nice to use kind words and be positive and specific
When you read a persons work and if you know about it or read about it it's nice to comment and tell them more information.
When your friend has published a blog about something that you know it is nice to have a  connection with the writer remind them about what you know that the writer left out.
It is nice that when you write a comment that you end with a question that you don't understand or what it looks like.
Make sure to always proofread before you post your comment.