You'll find perch wherever there is fresh water. Look for areas with natural structures: weeds, dams, submerged objects, islands, inlets, rocks, reeds and bridges -- any place where plants can grow. Plants attract bait fish and bait fish attract sport fish, so those are the areas you want to look for perch.
Perch school by size, so big perch swim together in deeper water and small perch hang together in shallower water. Catching one perch means there are more in the area.
If you fish from shore, you'll generally land smaller fish. Cast your line toward weeds, lily pads, piles of rocks, pier pilings and brush. Give the first spot you select several minutes; if you don't get a hit, try casting to another spot. Patience and a willingness to try different things will help you find fish.
If you're fishing in open water from a boat, you'll be fishing deep. Perch tend to congregate in deep water most of the year. Even in open water, perch will congregate around submerged objects, so the trick is finding those areas. Try this: Head into deep water, turn the boat off, and drift with the wind. Drop your line in the water to just above bottom (let the hook hit bottom and then reel it up a bit) and let it dangle as the boat drifts. Once you've located fish, drop anchor and cast. You also can try this technique while using a trolling motor.
Technology can help, too. Fish finders use sound waves to detect underwater objects. They display a graph on a screen that shows the depth of the water and any objects between the boat and the bottom. If the sound waves bounce off an object, it will show up on the screen. It could be a fish.