Forearm-forklift straps will allow you to move couches that weigh as much as 500 pounds. They're called forearm-forklift straps because you insert your forearm into the open loop, while using the opposite end of the bands to balance and lift the couch. Forearm-forklift straps are adjustable to the size of the couch you're lifting. Additionally, they promote the use of proper technique while decreasing the potential for back injuries.
Use furniture lifting straps such as those found on teamstrap.com. These moving straps work similarly in principle to the forearm forklift. However, instead of connecting to your forearm area, they connect over the shoulder and back areas. Navigating around corners as well as up and down stairs becomes easier with the help of lifting straps. It prevents you and your helper from straining while lifting your couch. The likelihood of personal injury and damage to your floors and walls is significantly decreased with the help of lifting straps.
If you're unable to use lifting straps, moving dollies provide another option for you to move your couch easily. Using a moving dolly or hand truck requires a bit more work, but it's a much better option than "free lifting" your couch. The advantage to using a hand truck is that you may be able to move your couch without assistance depending on the size, whereas you need another person if you're using lifting straps.
If you're using a four-wheel dolly, lift one end of the couch while someone places the dolly underneath the center of the couch. Slowly let the couch down on top of the dolly. Position the couch so that you can roll it to its destination. However, if you have many twists and turns or stairs to climb, a hand truck or dolly is not a good option.