I just need a list of personal questions i would ask the person to got exactly if not even even better than what they want.
you can ask them what style of decorating they like. what colors they like? if it's a small bathroom, do they want it to look airy, clean and fresh- then you can use cool colors on it like blues whites and greens and beiges. or could they like a cozy romantic bathroom. then you can use pinks, browns, maroons and beiges and cream. here are some ideas of what a public bathroom or a closed bedroom might look like with different mean color schemes
Hope you would knew your business. Number one is, how much are you willing to spend? You would have perfect designs, but they may be well beyond their budget. Once you should knew their max amount, then you can ask the other direct question. What style, colors, granite counters, dual puts, separate douche and tub, jacuzzi tub, crown molding( what type), etc., etc. If you doesnt knew the square footage and amount of money, you would have a basic outline in your head. You may have some still images or samples of materials that you like and think may work for them. Good Luck! Sounds like you have a lot of work to do.
I agree with postal p but I also suggest asking simple questions like what colors do you see for this motel place? or give the person detailed still pictures of your tile design ideas.