Equivalent Wattage - While lumens are the new standard, it helps to have an easily recognizable guide. Comparing an LED bulb to an incandescent will give you a rough estimate of just how well it will light a room. As a very ballpark figure for LED wattages, 1/4 or 1/5 the incandescent wattage value is usually close to what you need.
Lumens - Lumens directly measure just how much light the bulb gives out in total. On average, a 60-watt incandescent shines at 800 lumens, with roughly 50-100 lumens of difference above or below. The variance depends on manufacturer and age of the lamp. LEDs are directly rated for their max lumen rating and last much longer without dimming of the bulb.
Color Temperature - Your guide to how the light itself will look. Lower values are warmer, with 2700-3000K being a more incandescent "warm white" while higher temperatures like 5000K will deliver a very harsh "stark white" light.
Driver Content - Because of their design, LEDs do not typically run on AC voltage. Many LEDs require some form of driver to convert the voltage from AC to DC for proper operation. The majority of socket-based LED lamps are self-driven, but you should always check before buying to make sure that you buy both an LED and a driver at the same time if it isn't self-driven.