As discussed previously, the essence of the modern defensive style is the use of backspin and spin variation to force mistakes from the opponent and setup the forehand topspin counterattack. That said, here are my tips for the modern defender.

Tip 1 - Service

The modern defender needs to make the most of his own serves. He should always be ready to use the classic 3rd ball and 5th ball pattern used by attackers, and should use the same serves the attackers use to achieve this.
In addition, the modern defender should also allow his opponent to attack his serve, but the secret to this lies in forcing the opponent to put the ball where you want to receive it, so that you can begin the setup for your own counterattack.

Watch Joo Se Hyuk or Chen Weixing when you can, and notice that they are not afraid to give their opponent a long ball on serve, but that most of the time the opponent is forced to attack to where they are waiting - typically to the backhand where they use the long pimples to vary the spin and set up for their own powerful forehands.

Tip 2 - Tempt the Opponent

Don't make all your chops so hard to hit that your opponent gives up attacking and starts to push all the time. You need keep tempting him to attack by putting the occasional ball a bit higher or shorter so that he can start an attack. The spin variation that you use will keep him making mistakes. A good player will do this as part of his plan so that he is ready and waiting for the attack, whereas beginning players do it by accident and are caught unprepared.

Tip 3 - Hide the Contact

When it is possible to do so while maintaining good technique, take the ball below the level of the table so that your opponent's view of the ball is obscured.

This will make it that much harder for him to guess the spin on the ball. When combined with twiddling this can be a very effective tactic.

Tip 4 - Wait for it

The modern defender needs to fight the urge to prepare too early for his counter attack. An experienced attacker will notice the start of your stroke and switch the ball to the backhand side, catching you out of position. Anticipation is good, but guessing is not.

Tip 5 - Dare Your Opponent

If you have quick footwork, you can sometimes get away with standing further over to your forehand side, so that your opponent has a tempting gap to aim at on your backhand. He will be more likely to attack to the gap, so you should be prepared to quickly cover the attack and start using the long pimples heavily spin the ball in return, generally to his forehand. He will probably go with a slower crosscourt loop that can be attacked for a winner.

Tip 6 - Balance is Important

Not just your own balance, but the balance between your defense and attack. You will need to find the right blend for each opponent - sometimes you will have to attack more, sometimes less. Be aware of whether your current plan is working and be prepared to make adjustments during the match.

Tip 7 - Go Deep When You are Deep, or You'll be in Deep ...

In general, when you have been pushed back from the table, you will be better off placing your chop returns deep to the back of the table in the middle of the line of play so that your opponent cannot drop the ball short easily. (Note - many players will advise you to hit to the middle of the endline - this is not quite correct. Hitting deep to where you will be in the center of the line of play will work better.)
A planned short chop with float can be useful though, as many opponents will try a drop shot and should pop the ball up due to the lack of backspin. You had better be charging in behind your float though!

Tip 8 - Get Back

Both modern and classic defenders need terrific footwork to make their style effective. Usually the side to side movement is relatively easy - it is the in and out footwork that is the hardest and which is most often exploited by opponents. Practice coming in and going back until you are smooth, fast and balanced in both directions. Many attackers have only this one trick in their arsenal against defenders, so if you can take it away from them they don't have a Plan B.

Tip 9 - Stay Up

Refer to Tip 8 - and ignore that tip if you have accidently placed the ball high and short. If you try to go back you will be vulnerable to a wide ball on either side, or even a drop shot. Instead, stay in close and block the coming attack - it's surprising how effective this can be against an attacker who is expecting you to be going back from the table. Don't try to hit the ball too hard, just stick your bat out and put it back on the table - the surprise will do the rest.