The most emphatic and best way of becoming an expert in anything is to train another person on how he can do it. If you want to gain more knowledge in fishing then begin to train another person on how he can do it. You will have to take him along on your next fishing trip. If you begin to teach him then you be able to practice in an easy way in turn.
When you teach someone, you will have to recall all the knowledge and information that you already had on the subject from the beginning. When you train someone on how to drive then you should start from the basics, you have to teach all about mirrors, accelerator, clutch and gears. This is something that you do not mind most of the time. However, this revival about basic knowledge will be the base to build your expertise.
You will have an overwhelming feeling when you know that someone depends on you for everything he wants to do. This is the feeling that is better explained by the person who has felt it. This is why you will be finding parents teaching their children new things. Your student will begin to consider you as an expert regardless if you consider yourself as one or not. For him, you have everything it takes to be an authority and he will be relying on you for everything in this subject. The feeling you will get will enhance your confidence. Because you know that someone depends on you for his knowledge then you will try to make sure that you increase your knowledge in the area by reading more about the subject. You can even learn about the small things that you were overlooking so far.
As you teach many people or many times, you will be too conversant with the knowledge until you are able to recite it off head. You will be getting a good chance of doing non-deliberate practice using your system.
Another important point about teaching another person is that when you are teaching someone, you make sure that you are using the best, safest and optimal way to do something. What you teach will come from your own experience and the student will realize that there are things that he has to do on his own if he wants to improve his confidence as you did.
When you teach someone, you try to follow the book as you can. You avoid making mistakes because you are trying to teach someone how to do something and you cannot afford to lie to him.
If you want to become a real expert at something then being able to train yourself right away will be the best thing that you can do.