With hundreds of companies having already reported quarterly results, we're now in the heart of earnings season. The key to making smart investment decisions with stocks releasing their reports is to anticipate how they'll do before they announce results, leaving you fully prepared to respond quickly to whatever inevitable surprises arise. That way, you'll be less likely to make an uninformed knee-jerk reaction to news.

Let's turn to AFLAC Incorporated (NYSE:AFL) . The insurance giant is best known for its duck ads in the U.S., but the bulk of its business comes from risk-averse Japan. Let's take an early look at what's been happening with Aflac over the past quarter and what we're likely to see in its quarterly report Tuesday.

Stats on Aflac

Source: Yahoo! Finance.

Can Aflac insure success for investors? Analysts have largely stuck by their initial estimates of Aflac's earnings for the quarter, cutting their earnings-per-share calls by only a couple pennies. The stock has managed to climb about 5% since early November.

The big difference that Aflac enjoys compared to many insurers is that its losses are both geographically diversified and different in kind from typical property and casualty coverage. For instance, The Travelers Companies, Inc. (NYSE:TRV) and The Allstate Corporation (NYSE:ALL) both suffered severe losses from Hurricane Sandy, even though Travelers' stock rebounded after its quarterly report revealed that those losses weren't as bad as initially expected. By contrast, Aflac's primary focus on supplemental life and health insurance in the U.S. leaves it largely unaffected by all but the worst natural disasters, and its business ends up being relatively stable by comparison.

One long-term question the company has to address is how the Affordable Care Act will affect its supplemental health policies going forward. UnitedHealth Group Inc. (NYSE:UNH), WellPoint, Inc. (NYSE:WLP), and other primary health-insurance providers are looking forward to the individual mandate to bring in new customers, and they could be able to poach customers who currently rely on Aflac's supplements rather than having full-blown health coverage of their own. Aflac will have to work hard to retain those customers and seek out new ones from among the newly covered ranks.