I think it should depend on the job, but I have had experience in sales in the past and this is my advice to eejit.

If you are trying to set up an appointment with a future client, don't ask them when they are available.

That's too easy of an out for them to not want to commit to anything.

Tell them the date and time, you have available during the middle of your sales pitch.

Not the end.

By doing this, it narrows it down for them, and they are able to see that it wouldn't be that hard, because July 29th at 3 is when whoever is coming by, or when I have an appointment.

By the way the date was just the example.

I did sales for an air conditioning company and this worked like a charm.

I got comission every paycheck or almost every paycheck because of this little tip and advice I got from one of the employees.