Fast, clear feedback is crucial to gauging probabilities; for lessons, consult weather forecasters and professional gamblers.
"Most of us have to estimate probabilities every day. Whether as a trader betting on the price of a stock, a lawyer gauging a witness's reliability or a doctor pondering the accuracy of a diagnosis, we spend much of our time—consciously or not—guessing about the future based on incomplete information. Unfortunately, decades of research indicate that humans are not very good at this."
Advice from the article on how to you improve your skills at estimating risks: (1) Assign numerical quanitites, like weather forecasters saying there is a 60% chance of rain. (2) Track your performance. Was your guess right or wrong? (3) Then use the feedback to improve your estimating skills.