Can we talk about imagery? Websites need lots of it. A blog post looks naked without a photo, right? Without the dancing cat, this post is just a wall of text.
But there's one kind of image that's always the wrong choice--the one you don't own.
I know it's all kinds of fun to use a Ryan Gosling meme on your site. But it's a bad idea, even if you've seen others do it. You could easily get tripped up by either a legitimate copyright claim, or a scammer trying to scare you into paying a legal fee to make him go away.
If you think it couldn't happen to you, read this woman's experience.
Using only images to which you have rights is also just the right thing to do! Authors who would be dismayed to find their own ebooks pirated on a sketchy website should respect the work of photographers, too.
So where can you get cheap and free photos to use?
Deposit Photos has thousands of pictures, and some of the least expensive prices of any of the stock photo sites.
Wikimedia Commons collects photos for common use.
You can also use the advanced filter of Google Image Search to find photos which are "free to use, share or modify, even commercially." Look under usage rights to find this setting!
And be safe out there!