Especially when looping, you need a loose arm to maximize power. Many players literally jerk their arm backwards when looping. Instead, relax it into a natural backswing position, and then use the natural elasticity of the muscles to slingshot your arm into your forward swing. Think of your arm as a rubber whip and whip it into the ball with smooth acceleration. You should extend this thinking to the entire body since looping is a full-body shot - with power coming from the legs, hips, waist, shoulder, arm, and wrist - all part of one big whip that smoothly accelerates into the shot. Watch the top players and do what they do!!!

It's often difficult to judge how much spin you are putting on the ball when you practice serves. Without this feedback, it's not easy to improve your serves. So try this - find a large, carpeted room, and practice serving there. Spin the ball as if you were serving and try to control what it does on the rug. With backspin, make it roll back to you. With sidespin, make it curve sideways, perhaps aiming at targets. (Perhaps have a little fun by having it curve around objects.) Keep working on getting more and more spin, while still controlling it. To maximize the spin, accelerate the racket through the ball with the arm and wrist, and just skim the ball. When you can get huge amounts of spin this way, and can control it, then try it on a table.

Many players, when learning to loop or when under pressure, try to guide the shot consciously. This is a mistake and leads to a weak and erratic loop. Instead, let the shot go, accelerating smoothly through the shot. Don't try to "muscle" it - that just leads to spastic shots and a loss of control. Watch how the top players do it almost effortlessly, and with enough practice, you'll be able to do it. When you miss, adjust the shot on your next shot, and again let it go. If you still have trouble, there are two simple remedies: get a coach or copy the top players. And table tennis is a sport where you can absorb by watching - when you do so, your subconscious picks up on it, and can do a surprisingly good job of copying what it sees. One huge key - once you start looping competently, remember the feel of the shot - the entire stroke, from start through contact - and then just repeat. It's as simple as that!!!

If you don't have something that threatens your opponent, then you can't threaten the opponent.  So, how do you develop something that threatens an opponent?

You can't do it by just training everything equally each session. You need to spend a huge amount of time developing the things you can do that can threaten opponents. If you train everything equally, you'll tend to do everything at about the same level, and so will have nothing that threatens opponents unless they are weaker players. 

The first step is identifying what it is you might be able to do that will threaten an opponent. To use a common example, suppose you believe you can develop a very strong forehand. Then you need to spend a lot of time developing 1) your forehand; 2) the footwork to get into position to play the forehand; 3) serves that set up your forehand; 4) receive that sets up your forehand; and 5) rally shots that set up your forehand. 

Once you've identified the aspects of your game that you need to develop in order to develop something that threatens your opponents, the next step is to practice those aspects. And here you may face a problem. If you have limited practice time, you may not be able to get enough time to really develop those aspects. So what do you do? You make time - but perhaps only temporarily. (If you can't find the time to practice, then you simply won't improve.) Perhaps make a deal with yourself that you will put in extra practice time for a set period of time - perhaps six months to a year. Once you've developed those techniques, you have them for a lifetime! (Assuming you keep them tuned up.) 

Here's a tip on practice I've always advised to players: "Practice everything you do in a match, but focus on fixing the weaknesses and developing the overpowering strengths." A sequel to this might be that, if you can turn a weakness into a strength, your game will go up a lot. 

If your opponent is one who analyzes an opponent's game and adjusts to it, and is able to identify patterns and take advantage of it, you need to be unpredictable and vary your tactics. But many players, probably most, do not do this. If your opponent is not one who adjusts, then don't make the mistake of "over-thinking," where you try to mix up tactics that are lost on your opponent. Against the non-adjuster, just use the best tactic in any given situation while not overusing any one serve, shot, or technique so much that he gets too used to it. It's against the smart opponent who can adjust that you must regularly vary your tactics.

Now go look in the mirror. Are you an adjuster or non-adjuster? If the latter, it's time to adjust your thinking!!!