At the first conference I talked at I wasn’t really welcomed. I just went to the room where I talked (which was very small, they could have told me) and set up my own laptop and didn’t know if I was doing the right thing. The talk went terrible because it made me even more nervous.
Finding out at the last minute that my talk slot is longer (or shorter) than I’d expected is frustrating & difficult.
The conference organizers did not tell me upfront that I am not able to use my laptop on stage and my material needs to be passed to the A/V crew. As it turned out the AV crew expected a ppt presentation file which I could not provide since I use a html5 presentation kit. “Fixing” these kinds of issues right before hitting the stage sucks.
I hate draconian speaker contracts that make me personally liable if i can’t attend; I can’t sign a contract that binds my employer, and why would i risk my house when I get no personal benefit from speaking (because i don’t accept speaker fees; it’s my salaried job).
I dislike being told late that slides are 16:9 resolution/ must be CC-licensed, as I write my decks early.
I run workshops, and give conference folk a list of needed materials. There have been a couple of occasions where things would have fouled up completely without the emergency stash of post-it notes and sharpies I always have with me.
In an invitation email I want to know why I, rather than some other expert, would be an important addition to the conference.