Proper hand techniques are the crucial elements in learning guitar. But these are not ‘must use ‘ thing. You may seen even the some famous guitarist do not follow these techniques, and also you can have your own method. But this doesn’t mean these techniques are waste of time. Actually these techniques are adopted by many guitarists. These techniques help to acquire the necessary skills and improve your playing in very short amount of time. 

1. Right hand

Holding the pick is one of the crucial skill in playing guitar efficiently. The main benefit of this technique is, it prevents the pick from falling while playing and gives stability to the pick. If you hold the pick randomly, the pick may slip off and you have to readjust the position continuously. 
Hold the pick between your thumb and index finger. You have to hold the pick at 90 degree angle with the thumb. Make sure that pick is sticking out form underneath the thumb a half (or quarter) inch.
While playing or strumming  the chord, resting your pinky finger on body near sound hole helps in controlling the sound of guitar. It also provides the hand to have lesser degree of movement so that your hand does not get tired easily. This technique is also helpful in picking the note (which we will discuss later) and in palm muting. 

2. Left hand

Holding your thumb or placing your thumb also affects the playing. You have to hold the thumb on the back of the fingerboard on the upper side of the neck. Don’t put the thumb on the top of the neck (but this will help in some cases, which we will discuss later).  The strength to press the string is not due to thumb, rather it is due to the other four fingers. So  don’t press your thumb so hard (It may get your thumb tired). Rather try to press the strings hard. 
Your fingers should be spaced evenly. To do this put your index finger at any fret of any string. And put your middle finger on fret next to it, ring finger on next fret and pinky on fret next to ring finger. But while doing this you may find it is difficult to separate middle and ring finger. You can do some stretch exercises. While doing this you may feel that how the middle two fingers are coming straight onto the fret-board; and index and pinky fingers are curved slightly towards the frets.