Watch Your Fraud Data
While there are some fraud issues that hit all merchants, many issues will be specific to your business and even to individual products. Some products you sell might have higher potential for fraud than others or orders from certain countries might have a higher fraud rate than others.
Look directly at which aspects of an order lead most often to reports of fraud or chargebacks. Taking action in both your coaching and automated anti-fraud system against future orders of those types will do the most to optimize your bottom line.
Of course, after any changes, be sure to follow up and measure how effective your changes were on both your fraud rate and false positive rate (the rate of valid orders declined due to fraud suspicion).