If you did not write it, mark it as somebody else's. Bonnie McDonough devotes a whole post to the tag that sets quoted material apart, explains how to use it and why credit matters, and that concern for doing things properly is what makes the blog worth reading.
The post on pinging is a good example of her method. She found the advice contradictory, so she looked at both sides, explains what pinging actually tells a search engine, and is careful to say that it does not make anything rank.
There is a post on forgiveness built around a song and the true story behind it, and she goes and watches the story before writing about the song.
A post on ringworm in dogs answers the questions people actually search for.
One piece reports problems with customer support, plainly.
Read the quoting post if you share other people's material and have never thought about how.