Have a look at the wildlife around you when you go fishing and you will get a good idea of how the fishing might be.
When fishing gets slow take a good look around the place you are fishing. You will want to watch for things like squirrels and listen for birds. If fishing has turned bad chances are you wont see a lot or hear a lot.
You have to understand that fish are also a piece of wildlife. Many times you can make decisions based on what you see going on above the water.
So at the end of the day take the time to pay attention and when it comes to fishing chances are you will catch a lot more once you learn to read nature and wildlife a bit.