Anything that will help with your process of thinking, and nothing that will constrain it to a certain pattern or process.

Please read this link:

SYSTEMS THINKING: WHAT, WHY, WHEN, WHERE, AND HOW?

BY: MICHAEL GOODMAN

Analysis, synthesis, systems thinking and the scientific method: Rediscovering the importance of open systems

DOI:10.1002/sres.816

I am very interest in systems thinking is a holistic approach to analysis that focuses on the way that a system's constituent parts interrelate and how systems work over time and within the context of larger systems