What is an effective strategy for making good healthcare decisions?

This question can be answered differently depending on who is making these healthcare decisions.

As a healthcare provider/practitioner, evidence-based research, guidelines, or case studies should be used to make effective healthcare decisions. This is particularly true when making decisions about which therapies (pharmacological or non-pharmacological) to start a patient on because it provides well-researched reasons behind why a medication is preferred in a particular patient population. For example, evidence-based guidelines for the treatment and management of type 2 diabetes mellitus are the 2016 American Diabetes Associations's Standards of Medical Care in Diabetes. It is also important to use recent/up-to-date sources of information that applies to the patient's specific characteristics (i.e. age, gender, race, disease-state, allergies, etc). 

As a patient/care-provider, it is important to consider credible public resources when making good healthcare decisions. For example, there are "report cards" available that grades physicians and hospitals based on the care they give. By using these report cards, patients are able to compare different providers/institutions and decide which ones fit their needs. If looking for the best insurance plans, healthcare.gov is a great resource.