The best running socks are ones that are made from synthetic materials such as polyester, acrylic, and CoolMax because they'll wick away moisture. For winter running, wool blends such as SmartWool are also a good choice. Some runners choose to wear double-layer socks (WrightSock is one brand) for additional blister protection.
Although some runners like thicker socks for additional cushioning, others prefer thin socks for a "lighter" feel, especially in warmer weather. When shopping for running shoes, make sure you try on shoes with the socks you're going to be running in because some socks will require you to go up a half-size.