I was re-reading an old forgotten book off my shelves today - Conceptual Art by Daniel Marzona - and found an interesting quote:
"Your work isn't a high stakes, nail-biting professional challenge. It's a form of play. Lighten up and have fun with it." - Sol Lewitt
I believe that this is, more often than not, what makes the most of us get too afraid to let loose in our works. The more we are fed with input from fundamentals and other razz-ma-tazz that makes up preconceptions, we tend to forget to have fun.
Knowing the rules should give you the license to tip toe around the elements and principles. Screw the notion and never ending debate between conventional and non-conventional, thinking in or outside the box.
Stop being intimidated with your canvas and just WING IT!