To find the best evidence you need to:
PICOT is one framework for building a clinical question.
The following resources will step you through the process of creating an answerable question:
Formulate a clinical question
Self-directed online tutorial (from the University of Western Australia, Faculty of health and medical sciences)
You can also consider alternatives to PICO. This academic paper outlines some alternatives including COPES, ECLIPSE, PIPOH, PECODR etc) based on field of study (eg: medicine, OT, social work, speech pathology, oncology etc).
Introduction to Evidence-Based Practice from Duke University Medical Center Library and the Health Sciences Library at University of North Carolina