Competing in tournaments against girls is much different than competing in tournaments against guys.  I have played against many top female players including Shen Yanfei, Wang Chen, Gao Jun, Chiharu Yamazaki, Mo Zhang, Watanabe Yuko, Jiaqi Zhang, and many other Olympic level female players.  There are some general strategies that I have learned from competing against them.
 
Use Different Strategy
Most girls play quick-off-the-bounce counterdrives and smashes without much spin.  They are used to hours and hours of counterdriving.  If you stay close and play flat hitting against them, you have no chance to win.  So, try your absolute best to play much differently than a girl would like to play. 
 
Use Spin
Spinny serves work very well against girls because they aren’t able to produce as much spin on their own.  In previous blogs, I have written about serve return – that by producing spin, the receiver can control the spinny serve much easier.  Not only should you use spin on your serves, but you should use spin on your loops and pushes while keeping them low and deep.  Your female opponent will easily smash your weak loop for a winner.  So don’t loop weak.  If you can’t give a good low, spinny loop, then don’t loop – just push until the right moment.
 
Use Power
When you do decide to loop, the girl will probably try to smash your loop.  If you are able to loop with good speed, it will be extremely risky for her to smash your loop.  If she does consistently smash your loop, you should consider more variations in spin, speed, and placement.
 
Sometimes Lob
Most girls don’t train against lobbers.  If you need to lob, you can probably win at least 50% of the points just lobbing.  Due to a lack of strength and technique, most girls do not have enough power to hit through a good lobber.  As they fatigue, they will tend to use the drop-shot very often.  If you see a drop shot, be ready to step forward for the attack.  I would not recommend using lobbing as your plan A.  However, if your loop does get smashed, lobbing isn’t a bad way to save the point.
 
Continue to Change
Girls typically like to play patterns again and again.  Try to avoid a pattern like 2 balls to her backhand then 1 ball to the forehand.  If she notices the pattern, she will be able to gear up her smashing game.  By continually changing your shots from loops, to chops, to drop-shots, to lobs, you will be able to break her rhythm.