Find spike trails off the loop trails leading to lakes and streams. Look for waterfalls. Waterfalls have pools that hold big fish . Waterfalls also often mean that the water above is difficult to reach. Concentrate on streams flowing into and out of lakes.
Many anglers fish lakes and ignore the productive water of the creeks.
Look at the headwaters and feeder streams. Meadows often come out of canyons and I like fishing canyons. I can read a map. I can't tell you how many hours I have poured over national forest maps, BLM maps, DeLorme Atlases and topographic maps in search of that one stretch of river that most anglers either perceive is too high up or inaccessible. Let's assume you know how to read a topo map.