Check for membership in professional organizations Check for arborist certification Ask for proof of insurance and then phone the insurance company if you are not satisfied Get more than one estimate, unless you know and are comfortable with the company you are dealing with. Don't always accept the low bid. Evaluate work offered, skill, certifications, insurance, professionalism and price. An informed decision will protect you and your investment. Ensure your arborist will only perform accepted practices. Practices such as topping, removing an excessive amount of live wood, using climbing spikes on trees that are not being removed and removing or disfiguring living trees without just cause are unnecessary and could hinder or kill your tree(s).