Make Your Opponents Quit

Sun Tzu, in the Art of War, said

"For to win one hundred victories in one hundred battles is not the acme of skill. To subdue the enemy without fighting is the acme of skill."

In other words, it's the sign of a good warrior when he shows up on the battle field and the other side puts down its weapons. Conversely, having to constantly prove yourself over and over again may end up costing you. Think about all the 3-set matches that you have won in the morning only to be too exhausted for your afternoon match. Wouldn't it be more desirable to defeat your opponent outright in the morning match and still have the energy to do the same in the afternoon?! 

This goal can only be achieved by being the toughest, fittest and smartest warrior out there. Think: Federer, Nadal, Djokovic, Murray, Serena, Venus, etc. These players - through their presence and preparation - intimidate their opponents into losing before they've even stepped out on the court. Take Nadal, for instance. How many players think that they can outlast him in a 5 set match?! Not many. Not a guy you'd want to meet in a dark alley. He is so fit, strong and mentally tough that every player knows that he has his work cut out for him if he wants to take him on head-on. Many choose to not fight at all. Same with Federer. He intimidates people through his skill that he often cruises through the first 3-4 rounds of a Grand Slam without so much as dropping a handful of games, breaking a sweat or changing their shirt. Djokovic - same thing (see how he dominated the 2011 season). Due to their individual characteristics, they have bullied their opponents before they've even stepped onto the court. At that point, going through the motions of actually winning the match is merely ministerial. As a consequence, they are capable of going deeper into the draw than players who are, on paper, just as good but who don't possess the same aura. 

So the advice is to improve every aspect of your game to the point where people will lose the match before it ever starts. Your opponents need to think "geez..I don't want to play this guy. She's too fit/strong/tough for me. There's no way I'll win". Often, they will "go in the tank" before the match has even started. Make them doubt their preparation, skills, and commitment to the game. Don't just beat your opponents! MAKE 'EM QUIT! Send them the message that you mean business and this is not just a game to you.