If you hold bat too tight, your muscles in your wrist and arm will also be tight. This will restrict and slow your arm movement and make your strokes jerky. And you will find it harder to change bat angle when switching from one stroke to another, e.g. forehand drive to backhand drive. Overall you will have less feeling and control.
Instead, try to keep a looser grip. This will allow you to use your wrist more to generate spin. You will find it easier to switch between strokes and change bat angle. And you will be able to play faster shots, as your body will be more relaxed and able to move more freely. for any information click in this link Ping Pong
If you stand too close to the table, you will struggle to return balls which land very deep. You will have no space to play a stroke.
Instead, make sure you have some space between you and the table, something like 30cm-50cm. Now if the ball lands deep, you have more space to return the ball. If the ball is returned very short, you can still step in to get closer to the ball, but make sure you step back out again.
Don’t stand with your right foot much further forward than your left foot. Beginners often do this when playing backhand strokes. You can actually play backhands ok with your right foot forward, but you’re stuffed if the ball is then switch to your forehand. Your body shape will be wrong and you will find it difficult to play a decent forehand.
Instead, stand with your feet either square to the table (some professionals now do this) or with your right foot slightly further back than your left foot (this is the standard stance used by most players). With your feet in this position, you can still play very strong backhand strokes, but it is so much easier to switch to your forehand and play strong forehand strokes.