We learn from mistakes continuously throughout life, but this is helpful only if we face the same situation again. Normally, once the mistake is made, the damage is done and irreversible. Looking back, I can trace the cause of my many past mistakes to my pride. What I have learned is that we should consult the Lord who knows all things, in all things we contemplate doing. This may not be easy, depending upon your relationship with him. For example, if it's clear that you would need a new car, then you ask him to reveal to your heart what kind of car you should get, putting aside all your own preferences which he already knows. The Lord always help us choose wisely and sensibly, for he wants us to preserve our peace.