Fish instinctively like to do two things, eat and spawn. Spawning is the only thing that takes precedent over eating. Knowing the spawning season for a particular species helps determine where they're located. When fish are not spawning you need to know what they like to eat, so you will need to know where in the water column they are feeding. Are they feeding on the top, in the middle or on the bottom. Most fish have a preference but some can prefer all levels based upon time of day or season.
As a general rule most fish like structure. Many fish rest behind structure in heavy current, bait fish use structure for protection, however predators use structure as an ambush point. The difficult part is identifying where the underwater structure is located. Assuming you're not on a boat with fishing electronics, look for signs above the water such as walls, rocks and water patterns. When you are unsure, simply fan cast to cover all of the water before changing locations.