Make a list of your bad decisions and look for links. Were they all compromises, for example, or made hastily? When you identify a link, analyse the mental strategy that you used, and try deliberately using the opposite strategy for a while. If the problem seems to be haste, for example, delay the decision, and be ready to acknowledge any vaguer, subtler factors that come to mind.
Brainstorm before a decision, then sleep on it before acting. Like creative thought, good decision-making benefits from unconscious incubation, in which the brain drifts around, rummaging through memories that might be useful. Sleep is an extreme case of incubation, and your dreams may throw up important clues that make your decision clearer upon waking.
Mentally step back from the situation and ask yourself…