Oodles of variables come together to determine if you're a successful angler: lure color, the way you troll or retrieve your lures, choosing the best bait, etc., etc., etc. One that many people recognize is important yet fail to take advantage of is current—even in fresh water. Maybe I should say especially in fresh water, because the absence of tide-driven currents makes wind-driven currents and river currents even more important, in many cases.
Why? It's all about the bait.
Predator fish do not commonly respond to the current to "rest," or hide from it. With the exception of fish living in a constant, strong river current (like rainbow trout in a fast-moving stream) this is a common misconception. Rather, they use it to their advantage to attack bait that is dislodged, disoriented, or ever so slightly handicapped by the moving water.
The prime situation for these predators? Areas of no current that meet a confused current. This makes it harder for bait to maintain position, and to predict how and where the current will move it. You'll often find this situation in areas where currents hit structure like bridge pilings, points that jut out into open water, and underwater troughs or humps—all known to be prime fishing spots.
So, how are you going to take advantage of this? It's pretty simple: when you're in an area that has zero current and you're not catching fish, move. In a lake or reservoir this might mean shifting out of a quiet cove and over to a spillway. On a bay it might mean running across to the other side. And in the open ocean it may mean simply looking around until you can find an area where two bodies of distinctly different water collide.
In short, we're back to one of the cardinal rules of fishing: if the fish aren't biting where you are, move. But if you take current into consideration as you make that move, in the long run you'll catch more fish.