Use a grub as your lure. Search for a fish. Make sure you have 12-16 meters of line. Once you find a fish, reel in your line to about 6 or 7 meters. The fish should bite -- be quick when pressing L. You may have to try a few times due to the sizes of the fish.
Save your game and go to the "Buy Tips" menu. Buy the tips and make a note of them. Then go back to the "Save" menu, but do not save the game. Instead, go to the "Load" command and load the game that was saved earlier. You will still have all your points and will know the tips.