The GUI can be scaled in size, I have mine fairly small in a corner of my screen, mainly for the experience percentage of all toons.
You could have a large GUI much easier to see.

Chat warnings to the channel of your choice is an option.

I've gone with Raid Warnings in big letters across the middle of my screen.
You can configure it as you choose, "Slow down, you're going too fast" or "Follow Broken".. etc.