Keep context in mind
Will it be at “normal” kiosk height or a table-based unit? Will it be in a store or another place, like a lobby or a mall? Understand the environment that the Ui will be in.
Make big buttons
People will be using their fingers, so you need to provide big target areas. Remember Fitts’ Law (and if you don’t know about it, then you should probably look it up).
Keep it simple and obvious
Users are not going to want to spend any time figuring out things – they are (probably) standing and (most likely) just want to do something very quickly. You may be designing a “browsable” kiosk experience (such as in a museum) but most kiosks are about supporting quick tasks.
Simple natural language
Avoid jargon terms – use simple Non-verb combinations. “Check Balance” Or “Search Tenants” works – “Check your current bank balance” or “Search Tenants in this building” does not. Each extra word increases clutter and the likelihood for confusion.
Design for impatience
Be very neutral in the tone of voice any content the kiosk provides – if you try and be “cute” you may tick off the end user, who has no time for “cute.” Also, align with the content guidelines that the company has (and if they don’t have such guidelines, ask why and help to define it for them).
Offer a Spanish language version
If you are designing a kiosk in the US, offer a Spanish-language option/version. If you are in another country, then identify the two major languages in the region and support them.