nothing, and lots of it

A related lesson, learned from several client meetings:
I didn't use "Lorem Ipsum" latin filler text in mockups or prototypes shown to customers until a few meetings went like this:

Me: So, here's what the proposed home page will look like, and you just simply click on the discussion ar...

Client: What's that paragraph say about healthcare funding getting slashed?

Me: What? Oh, that. I just copy and pasted the first story on Yahoo News' medical news page, I thought it'd fit as filler text since this was a medical site. Now about the functionality of the featur...

Client: Well, can we change that? I mean, I don't want to look at bad news when visitors see the site.

Me: I just put that in for this photoshop mockup, it won't ever be seen by anyone. Now about the new proposed sub-sectio...

Client: Ok, but if you could change all the mockups, that'd be great, I don't want to show these around the office with that bad news on there.

I've used Lorem Ipsum as filler text from then on.