I think it depends. If I take my time with a decision, my head is definately involved. I think most of my decisions are made with my head. However, sometimes, I just do what my heart tells me and ignore my head or don't consult my head. I think this can be bad and good depending upon what the decision is you are making.
I tend to try and use my head first. I try to take myself out of certain situations and then look at the whole picture before I make any decisions. Of course sometimes my heart wants to make some decisions, but not without me looking at all levels of any given situation and using my head before I set out a set decision.
My soul leads and my mind follows. I tend to think thats a greater power trying to lead me, and also my inner self leading me. Somtimes when my heart reaches beyond what is allowed, my mind steps in. i think one would be much happier following their hearrts, its more free.
I believe that, for the most part, if it's a big decisions and it's the right decision, my head and my heart will both be in the same place. Now, that's not necessarily true for little decisions, but the major decisions I have ever made in my life I depended on both my head (knowledge, wisdom) and my heart (intuition). I have been faced with sitiuations in regards with other people where I had to go with what my heart was telling me to do. I'm so analytical, though, that I usually have to analyze a situation from all angles.
I suppose it all depends on the situation. Usually, I try to make all decisions with my head since I consider this to be, the right way to think "logically." I have made a few decisions in the past with my heart and all of those issues were related to relationships. Some decisions were good and others were bad! I think the heart makes you a little too emotional and this may severely impair your judgement! I guess this is why this song was created by El Debarge, "The Heart is not so Smart!"