I love the title of your post

I would focus on the soft rather than the hard. Instead of thinking of a subject or industry, think of the types of interactions you enjoy:

Do you like working with people?
Do you like working alone?
Do you like being outside?
Would you want to work the same hours every day?
Do you like helping people?
Do you want to work in a very structured environment where everything is predictable and there are rules to follow?

etc, those kinds of questions. What is it that appeals to you about your dream job?

I also highly, highly recommend taking just any old job that sounds mildly interesting to see what it is like. The best way to learn what you do and don't like is by trying. I've surprised myself by finding out that what I think I want in a work environment isn't that much fun in real life (like you learned).