I, as well as many others here get paid commission (by the jobs we sell)and our time is as valuable as yours.
Here are some tips to help us help you.

1. Cancel your appointment if you cannot make it or hire another company before we get there.
It is cold out and we are all very busy. We understand if you cannot wait for us to get to you. We all need heat.
If you cannot keep an appointment or hire someone to do your job before we can get there, please cancel your appointment.
There are other customers that would love to have your appointment spot.
When we drive to your house for a scheduled appointment and another company is there installing your job, we just lost money out of our paycheck and another potential customer is still without heat.

2. Put up your dogs.
Even if we say the dog doesn't bother us, IT DOES!
It's hard to concentrate on talking to you when a dog's nose is stuck in your crotch or barking its head off.

3. Clear the area around your equipment.
I don't feel like breaking my leg or having to do a gymnastic routine to climb over your Christmas decorations.

Again, these are just helpful tips.
Maybe others can post some suggestions.
maybe BC1 can sticky this to the top?