CHICAGO ( TheStreet) -- Employee benefit packages vary as much as the companies offering them. But any small business that wants to attract and retain productive workers needs to be familiar with the most common benefit trends. Offer nothing but a bare-bones package and you may have trouble filling job openings with qualified candidates; offering up too many extras may be financially unsustainable over the long run. Over the past few years, the general trend in benefits was to squeeze out any and all possible savings. But as fears of another recession have lifted, companies across the country are gradually re-investing in their human capital. Recently, the Society for Human Resource Management published its 2013 HR Benchmarks Trendbook, which gives an overview of how U.S. companies are spending on benefits while highlighting impending changes in the human-resources landscape. While some of the content is geared toward large corporations (such as the section on relocation services), much of the information can be used by small businesses to determine if they are competitive as employers. Here are the top four human-resources-related issues to keep an eye on in the year ahead: 1. Salaries For the average U.S. company, salaries make up about 40% of operating expenses, regardless of the size of the business. The average compensation for private-sector employees was $30 per hour last year; benefits other than salary accounted for 30% of the total. But the biggest trend in compensation isn't reflected in such averages. More and more companies are moving toward differentiation rather than set salary scales, with how much an employee makes directly tied to their productivity. Now that many businesses are easing off the salary freezes common in 2009 and 2010, the question of who gets a raise and how much is being debated carefully. According to the report, companies that are upping salaries gave a meager 1% to low-performing employees last year. By contrast, above-average performers were rewarded with raises of 4-5%.