• There is no more serving right: the side which wins a rally will get a point no matter they are serving or not. The side who wins will serve the next point.
• Serving from the left or the right? This depends on the score of the serving party. If the score is zero or even, the team will serve from the right. If the score is odd, the team will serve from the left.
• Should you and your partner switch service court (left to right, right to left)? Only when your team serves and wins the point. Therefore, when your side is not serving, don’t switch side. When you lose a point, don’t switch side. When the other side serves and you win this point, don’t switch side. Otherwise, switch.
• Like singles matches, a doubles match consists of 3 games of 21 points.

Most people string their rackets at 21 - 23 lbs.

The strings are like elastic band. At lower tension, the strings will actually be less stiff and more bouncy. The bounciness will actually help propel the shuttle and it is good for beginners who have less strength.

If you have a lot of strength, then high tension makes sense. High tension requires you to hit it with more force.  However, the sweet spot (the area with greatest repulsion) decreases with higher tension. Imagine that if your strings are as hard as brick wall, then there will be no repulsion and you will have to rely all on the strength of your arm.  Sometimes higher tension can hurt you as you always force yourself to hit harder.

Thanks Herbert!

So for Hong Kong, one should use 76 - 77. In China, 76 is used during summer and 77 is used during winter.  In places like Sweden or Canada, one should use 78-79. 73-74 should only be played in high altitude regions like Yunnan or Colorado.

1) Always move back to the center of your court after you hit the shuttle every time

2) When you try to move backward,  you should not step back with your head and face facing the opponent’s court. This would be very cumbersome and hard to balance your body.

Instead, you should rotate your body for around 90 degrees so that you are more or less facing the sideline of the court and then move sideways to the back court. You would be able to move much faster this way!

• The racket must hit the base of the shuffle. You can not ruin the shuffle by hitting the feathers!
• Some part of your two feet must be in contact with the ground. That means you can not jump and serve.
• The racket must be in a downward position when hitting the shuffle so that the head of the racket must be discernibly below your hand that holds the racket. See diagram below. Actually, thanks to the comments of a reader, the rule now says the shaft of the racket at the time of contact must be in a downward position. This actually allows a higher contact point and the serve can be flatter. Under this new rule, all serves in the picture below are actually correct since the shaft is in a downward position.
• The entire shuttle must be below the server’s waist at the time of contact between the racquet and the shuttle.