Your heart should be your conscience. Emotions are very important. Making a decision without emotions is dumb-even if making a decision without logic is crazy. I prefer crazy. Emotions are the guiding forces that make us choose stuff anyway. It's impossible for most people to be all brain and no heart.
Any sort of decision making should be done with your brain. Not what some people will say is that you need to go with what you feel. Well, the brain is what controls emotions or feelings, not the heart. The heart is only an organ that pumps blood through the body. Any emotions associated with the heart actually belong to the brain.
While acting from the heart denotes sincerity, urgency, and favors the carnal needs the most, acting from perspective of the brain usually proves more beneficial. While acting from the brain, an individual can utilize numerous mental processes simultaneously to effectively think their way through any situation. One can measure possible outcomes, and results, and act accordingly.
Logic comes first, it is your intellect to break down thing and define them. To understand and investigate. To think critically and to think relatively. Thinking with your heart is a deception, as it is a feeling. Not factual evidence or knowledge. It is just that, an emotion, a chemically unbalanced feeling. The real world is different, so in a sense, your heart decieves you. Your brain informs you. There is a big difference. The best position to be in, is to allow the brain to be in control.