What's the most efficient way to show something you've posted on Craig's List?

I’m selling a few things on Craig’s List right now, and I’m finding that flaky people are wasting my time. We’ll speak, they’ll tell me they’re coming by, I give them an address and time, and then they never call or show. I know you sorta buy the ticket, you take the ride with CL, but this keeps happening over and over and I don’t have the time for it. How should I change my approach, going forward? Only show it between specific hours on specific dates? What’s the best way you’ve done it so that it doesn’t wind up being a big time suck?