If you treat them right, trees can shade your house, beautify your property, and even save you money on energy bills. But diseases, pests, or extreme weather can impact the sturdiest oaks. And even healthy trees need a little branch management in the form of regular pruning or the occasional checkup.

Here’s our advice on how to find a good tree care outfit—and how to know if your woody friends need work in the first place. We also have ratings of area tree care companies, plus tips on managing them and keeping your trees healthy.

Before hiring any company, obtain competitive bids from several. For tree removal jobs, our undercover shoppers found big price differences when they obtained quotes from companies for the exact same work. It’s pretty easy to collect proposals from companies. Typically, you don’t have to be home when bidders are looking at the job—but do include a thorough description of the work in a written contract that specifies who cleans up afterward, hauls away debris and wood, and removes the stump. What is not specified in writing is very unlikely to get done.

Also, check whether a company’s liability insurance and workers’ compensation insurance are currently in effect. Ask to see certificates of insurance, and call the company’s insurance carrier to verify. This is a serious concern because high-powered equipment, heavy branches and trunks, lofty heights, and proximity to power lines make tree work dangerous.