This is why getting an estimate is handy. One company might say three days while another company says three hours.

Get written estimates from three equal companies to compare prices and understand the scope of the job, which leads into the next question.

You don't want massive power equipment driving over your lawn and flowerbeds causing collateral damage unnecessarily. If they are going across your lawn, make sure they know the locations of sprinkler heads or other objects that may be damaged.

It may be a good idea to photograph the area before work begins so you have a record in case there is damage. Make sure you understand how they will clean up during and after the job.

The Occupational Safety and Health Administration (OSHA) requires that personal protective equipment be used for any tree care operation. A reputable tree care service will require their workers to be protected.

What does their company truck look like, is it well taken care of? Is the truck clean and in good shape? If they don't take care of their equipment, do you think they will take care of your tree and property? Do they have a website? Design and content can give you a sense of their professionalism, as can the appearance of the vehicles they use on jobs. That can give you an idea of how they run their business.

This is another poor practice, particularly for large, healthy hardwood trees and would indicate that you should continue your search.

Unless you're removing the trees, demand they not use spikes, which causes unhealthy wounds.