Clinical practice guidelines (also called CPGs, guidelines, and practice guidelines) are statements that include recommendations intended to optimize patient care. Guidelines are informed by rigorous systematic review, synthesis of medical literature, and an assessment of the benefits and harms of alternative care options (Institute of Medicine, NIH). For more information about how guidelines are created, look at the Mayo Clinic primer on the topic.
One way to look for CPGs is through large repositories created specifically for guidelines.
You can also find plenty of guidelines in healthcare and medical databases.
Evaluate the quality of a CPG before you take into consideration its recommendations. Check out these resources to evaluate any CPG.