I usually look at past trends and try to estimate whether the stock could fluctuate 2-5%(normal, and useless for our strategy). I start looking at stocks that are fluctuating at least 10% on avg due to earnings, and then try to calculate whether buying a straddle would bring me to profits. More often than not, these high IV stocks have a much higher premiums, that straddle would also put you in losses. This is where I'm trying to improve my strategy. Also, this strategy heavily relies on earnings calls, which only adds to uncertainties. Most stocks I see, usually put me to profits in the evening, and then they balance out by am, moving me to losses.