What would a blog be without pictures? Just a long text message.
I try to be explicit about where my images originate. A favorite site is http://www.photoxpress.com. At PhotoXpress one can download high-resolution, royalty-free photos and artwork; their only requirement for use is attribution. I usually get this on the page, and I usually link unaltered images to their web site. Occasionally I will forget to put the attribution on the post, so I hope this acknowledgement of my usage will help cover my butt.
At other times I search Google Images with the criteria "licensed for reuse." Once again, if you click on the photo you will generally be taken to the original source. Depending on the license requirements, I may also acknowledge the source in the caption or elsewhere on the post. I also use logos and other "official" images from web pages. If I am blogging about an organization and I feature their logo with links back to their site, I consider it a reasonable usage.
Sometimes I use images I have photographed or otherwise created. Yes, I do have some rudimentary skills in these areas.
My key message here is that I do not want to steal intellectual property. I try to use legally obtained images at all times, and I try to always provide links and attribution.
We should all behave this way.