We really hope you stick around a bit, read further, and explore what we have here. But if you're in need of a quick and dirty, what do I really need to know, this is your place. Here are our most succinct combined pearls of wisdom.
Not just anybody can do VUI design. It's an established industry made up of professional designers, many of whom have degrees in disciplines such as human factors or linguistics, and who often have years of experience translating this knowledge into effective VUI design. If it's simply not possible for you to get a VUI designer to work on your project from the ground up, consider, at the very least, having one do a heuristic review on your design.
Think about the dialogue from the callers' point of view.
Strive to design a logical flow that matches callers' expectations.
Speak to callers in terms they understand and expect, using intuitive, everyday language tailored to the caller base.
Develop a succinct style guide before writing dialog; some designers approach this using a persona to embody the company brand and to inform the style of language.
This is spoken language, not written language. Think screenplay. Read your prompts aloud, all the time, to everyone.
Test at every stage, with real callers. All VUI designers (regardless of experience level) learn something new when they conduct usability testing.
Be willing to think outside the box, as each design situation is different and may take creative solutions to unusual problems. That's why we're calling these guidelines instead of standards.
Write sample dialogues before you dive into full-scale design, and practice them out loud as conversations.
Keep in mind technological restrictions/limitations and understand the technology.
Don't let development drive the design.
Understand the business requirements first.