When it comes to a point in time when you need to decide -- either you make the decision or you let circumstances dictate it. Take possession. Decide to decide. In order to decide you need:
1. Identify and fill in the gaps of what you need to know.
2. Find someone reliable that you can ask for information or at least, you can ask to hear out your thinking process.
3. Determine how much you need to find out for yourself versus how much you can ask others for (and rely on others for).
4. Remember my comments on thinking fast and slow. Make sure to gear your decision based on its priority and your intuition about it.