Need suggestions for my startup

When there are some risks for your startup how do you usually handle/communicate with it?
I’m an interpreter & tour guide in Guangzhou, China. Recently I just started sourcing along with my interpreting service. Recently I got some potential clients from different platforms but once I asked some simple questions they started to ghost on me?
Ex, a client said he is coming on 27th of dec and he wants a few days of me, but he didn’t say what days he needs me. I just asked him very clear: what exact days and do you need a car to drive around the factory. He just read my message on WhatsApp?
Another one: some clients come to buy replicas. TBH it’s not cheap at all and usually around 300$ and I just had been nicely told a client but he suddenly disappeared too.
TBH I prefer some ppl just reply the reasons but why most ppl like to waste time and play cards? Also I hope I don’t sound pushy cuz I just wanna confirm my time and provide a good service.
Since I usually charge by hourly im thinking to take deposit first otherwise it’s wasting my time. I wanted to ask everyone when you start your own business how do you make clients respect your time?