My absolutely new favorite heuristic for decision making comes from Mr. Bezos:
Is the decision costly to reverse (costly as in time / money)?
No → Make a decision fast.
Yes → Take your time, consider alternatives, talk to people, think some more.
Just focus on the problem. Let imagination flow, but just focus on the problem, on the obstacle. Don't get lost on solutions, just inundate your mind with the problem, on the bad aspects, don't try to make you feel good with wishful solutions.
Then let it rest. Or keep ruminating. It's amazing how fast, and how frequent, you get some kind of epiphany or eureka moment.
Then do numbers or study your answers with a rational mindset.
Values are also and awesome and usually unknown compass. "Get out of your mind and into your life" from Steven Hayes has a great definition of what values are. It's a great book, I know about it from hackernews.
This book also tells a interesting idea. Some times you don't have to decide, you have to make a choice. A choice is arbitrary, there a lot of crossroads in life which don't have a objective solution.
