Fish like to lie near banks, particularly where there are over-hanging trees and bushes or even rushes and grass. Fenced banks will encourage such growth as stock will be prevented from grazing right up to the river's edge. Caterpillars and terrestrials may fall from trees overhanging rivers and streams, giving trout a perhaps unexpected meal. As well as falling, insects can also be blown into the water. Over-hanging trees and bushes provide much needed shelter and protection from predators overhead.
Banks can often be under-cut, particularly on the outside where the water flows faster.
Such an under-cut will provide a first class lie for one or more fish. Look for fish where fast water meets slower flows. Trout can rest in slower water and dash out to intercept food flowing by in faster water and then return to digest their meal in calmer conditions. Trees growing near the water's edge or ones that have fallen into a river will provide a number of potential lies. Another good place to to cast a fly is close to a line of foam.