 You can get away with using a helping hand or third hand tool when soldering small PCBs, but for holding anything larger, you should go for a vise. The old standby, Panavis Jr., works great for boards under 3 inches. And for boards up to 9 inches, Panavis also makes the PV350 Work Center, tricked out with rubber grip jaws and a built-in parts tray. The Pro's Kit PCB Clamp can also hold large boards, plus it easily flips them, which is handy for routing jumper wire on proto boards. For SMT boards, you'd prefer not to flip. A stick vise keeps the board stable and flat, allowing you to steady your hands on the table. Alternatively, you could go for one of these flat circuit board holders, which are normally used for cell phone rework, but they're great for pretty much any SMT soldering.