At the very beginning of the game, I didn't have much trouble catching any fish: put the bobber in the water, wait for the fish to bite hard enough for the bobber to dip under the surface, press A. Not too complicated. However, in the few days since, I've had noticeably worse luck with my fishing: the fish will quite often escape when I attempt to reel it in, despite the fact that as far as I can tell, I'm not doing anything different. When I'm depending on fishing for my income to some extent, it can be a little frustrating.
Am I doing something wrong, or do fish just sometimes escape, even when you use the proper timing? Is there anything I can do to increase my success rate with fishing?