You put your boat in the water, and then you set there just looking at that huge lake. And you think about the 80/20 rule. The rule that says 80% of the fish are in 20% of the water.
But which 20%?
It's a lead pipe cinch that to catch fish you have to fish where the fish are. So step one of a successful fishing day is locating fish. Step two is what and how you present to them. Step two is another story for another day. First find the fish.
There are exactly twenty two point six three nine gazillion variables to consider, and if you do it right you'll locate the fish to within two microns. Or...you can consider just five things, five big broad things, that will narrow the search area down to a manageable size.
First thing to consider is time of year. Every species has it's own schedule and rules, so you'll need to do some basic study on your favored species, but...they all have some general patterns that are similar. Is it early spring? That could mean they are spawning. Is it mid-summer? That could mean they are following bait fish up creeks. Late summer? Maybe they are down deep. Thinking about seasonal patterns means thinking about the geographic contours of the lake. A good contour map is invaluable.
Second thing to consider is water temperature, and this too goes with seasonal thinking. In the winter you're looking for warm water areas. Summer time means looking for the thermocline, looking for water a couple of degrees cooler than the average.
Third is water level. Most lakes will vary somewhat from month to month. Some will vary a lot. Heavy rains can raise a lake quickly. Droughts can lower them to severely low levels. High water in the summer might indicate fish feeding in freshly flooded areas, getting all those grasshoppers and other bugs. Low water can mean looking for deep spots.
Fourth is water color. Stained water, water that is murky, hard to see through water can mean fish in shallower areas longer during the day as they will be invisible to the birds of prey. The opposite is true of clear water. Generally speaking clear water means the fish are going to go deeper.
Weather is a big one, and a quickly changing one. Amount of sunlight, cloud cover, barometric pressure, temperature, rain, wind...these all play a factor in where to find fish.
Study your fish. Learn what they are likely to do in all of these conditions. When you know that a bright hot summer day with high barometric pressure in clear water conditions means to look deep near sharp drop-offs to shallow night time foraging areas - when you know that on a cold winter day with heavy cloud cover and a dropping barometer and wind from the north east means to look for shallow flats on the south west edge of the lake where a large creek comes in - then you have a check list of where to look.
Learn your fish species' habits, then use this 5 point check list. You are likely to find that 20% of the lake in record time.