Listen for unusual noises that could be caused by a binding cable or a nut that has fallen off inside the control surface. Be sure to deflect the controls so that any water that has collected inside can drain out. Before takeoff, it is important to check the controls again. Here you want to see that the yoke or stick in the cockpit can manipulate the controls in full deflections without any impediment. Remember, too, that the checklist says free and correct .
Many pilots simply row the controls through the motions without looking to see what they're doing.
A simple trick to check ailerons is to grasp the yoke or stick so that your thumb points upward. When you rotate the wheel, your thumb will point to the aileron that is deflected up. Believe it or not, many of them occurred because the pilot simply neglected to remove the control lock, usually the first item on a preflight checklist. Many airplanes have items that need special attention. For Cessna singles, pilots should always ascertain that the fuel caps are snug and seated properly.