Aim for rising fish. Common lake hatches are damsel flys for which there are patterns as well as small black midges which can be imitated with a griffith gnat pattern. Sometimes just lobbing out a big attractor pattern such as a stimulator or a royal wulff will attract fish, it helps to give the fly a few twitches and make it "dance" on the water. I use floating flyline for this method. Yes...fly fishing can be exciting!

If there is no action on top I usually use sparsely dressed woolly boogers (no bead head) and soft hackle nymph patterns such as a pheasant tail (obviously) on an intermediate sink tip line.

Cast out and let the line sink occasionally twitching the rod tip.
Retrieve the boogers with slow strips and pause between each. The nymphs I allow to settle and then slowly raise the rod tip and "hand-line" the retrieve, the slower the better.