Some of both. For instance, when it comes to making a purchase, I start with the head.
Do I have the money for it? Do I need it?
If it’s a matter of want, rather than need, then it becomes more a matter of the heart.
Am I willing to give up having something else in order to afford this?
If I lead with nothing but my head, then I wouldn’t have things which aren’t a necessity–like art. But if I lead with my heart, then I’d have something I really didn’t want–debt.
Writing my book is also like that (https://keripeardon.wordpress.com/). I’ve written it just because I just wanted to write it. Now that it’s written, though, comes the practical part: querying agents, designing a book cover, creating a presence on the web. All art must have a practical component, as well as the aesthetic.
Have I ever mentioned I’m a Libra? It’s all about balancing the scales.