If no preparation is needed, make certain that you're on the water with your trotline deployed as the sun rises. Any earlier is usually unproductive. In most situations, a trotline should be worked where the water depth is between 4 and 20 feet. The trotline is usually set parallel to the shore where the bottom drops off. The beauty of a trotline is that it allows you to cover vast distances so that your odds of finding a hot spot are greatly increased.
Watermen say that running a trotline over a shell bottom yields more crabs.
The beginner, in particular, is advised to work his line with the tide or wind. It will be difficult enough without the boat being blown or pushed the wrong way. Starting upwind, throw the lead anchor overboard and play out the line as the boat moves forward. When in doubt, let the boat drift while playing out the line. Unless conditions change, you can be assured that when you return to your starting point, the boat will drift in the same direction again.