Perhaps the greatest lesson I've learned about making major decisions is the cost of making the wrong decision. The greatest time waster in our lives is the time we spend undoing that which ought not to have been done in the first place. Usually, we can recover if we make a bad choice. Sometimes, however, we can't. Never make a decision that bets the entire ranch on being right.
Most decisions are obvious given enough information and time.
When we don't have our facts straight and when we are hasty. Keep collecting data. Write it down so you don't forget it. The mind by itself may blow one small fact all out of proportion. Writing it down puts things in perspective.