Back lift :
The prime requirement for a well executed stroke is the back-lift. This is the backward lifting of the bat in preparation for the stroke to be played. It is thus vital to know when, 
where and how to take the back-lift. You must have often heard a commentator saying that a batsman has played a flowing drive. This flow depends largely on the batsman’s back-lift. As soon as the bat reaches its peak in the direction opposite to the stroke to be played, the downswing must start, thus resulting in a pleasing stroke. Sometimes, even your opponents appreciate a fluently played stroke.
Direction of the back-lift:
Old-fashioned coaches over emphasise the fact that the bat has to go back straight in the back-lift. This zeal to be technically correct creates more problems for the batsman. He starts worrying more about where the bat is going in the back-lift rather than focusing on the other, more important aspects of batsman-ship. 
The batsman’s primary aim should be to bring the bat down straighter to meet the ball with the full face of the bat while playing any stroke. Ultimately, it is the batsman who meets the ball with the full face of the bat – either in defence or in stroke play – who gives the least opportunity to the bowler and is successful most often.
Most of the Test cricketers with whom I have interacted are of the view that if the bat comes down straight to meet the ball, then one should not unnecessarily worry about where the bat is going in the back swing. Rahul Dravid, Vivian Richards and Karsan Ghavri are prime examples of unusual back-lifts – or shall I take the liberty of calling theirs a round back-lift? But they are great performers because they bring the bat down straight in the down swing to meet the ball with its full face.
Ideally, the straight back-lift is recommended so that it would become easier for the batsman to bring the bat down straight. But if you are regularly bringing the bat down straight and meeting the ball with its full face, then don’t worry overmuch about your back-lift.
Timing the back-lift is vital
When to lift the bat :
Timing of the back-lift is one of the most important factors in good batsmanship. It not only depends upon the individual style of the player, but also on how early he judges the line and length, the type of bowler, the pace of the wicket etc.
There are some general guidelines as to when the back-lift should start. For a spinner, you start the back-lift after the bowler releases the ball. For a medium pacer, the back-lift starts when he is about to release the ball and for a fast bowler, before he releases the ball. Everything depends upon the bowler’s pace, and how well the batsman is moving his feet.
But remember that there is no hard and fast rule which every batsman could follow to get his timing of the back-lift right. It is something that you have got to find out for yourself, for something that works for you might not work for someone else. Work in the nets, consciously, keeping the above tips in mind and by the trial and error method, you should be able to find out what is right for you. With regular practice, however, the timing of the back-lift becomes automatic and is then controlled by the sub-conscious.
Keep in mind that the timing of the back-lift has to be precise. If you are late into the back-lift, you may have to come down on the ball hurriedly and jab at it. If you are early into the back-lift, you may have to wait for the ball to come to you, thus breaking the rhythm of the stroke. In both cases, the flow is missing and your batting looks unattractive, though you may score some runs. What is more, an intelligent bowler will detect this flaw and exploit it to his advantage.
Stiff front elbow leads to low back-lift
The how and why a low back-lift :
Some batsmen keep their front arms so stiff, in the stance, that in the process the front shoulder remains higher than the back shoulder. Since the front elbow is not bent, the 
batsman is forced to lift the bat backward with the bottom hand. It is also observed that these batsmen have a low back-lift and while driving, their front shoulder does not move down before impact. Hence, batsmen with low back-lifts sometimes tend to lose control over their front foot strokes. Especially when trying to put too much power. They would also hit horizontal strokes, like the hook and the pull, up in the air. The low back-lift will allow them only to hit the ball from the bottom, upwards. This is especially true when the ball bounces more than expected.
Batsmen with low back-lifts could do well to remember that they should focus on timing rather than hitting the ball with a lot of power. Ajit Wadekar and Kepler Wessels are prime examples of players with low back-lifts. But see their records at the highest levels and you will be convinced that a batsman with a low back-lift can do wonders if he plays within his limitations and times the ball well. Such players are also past masters at deftly using their wrists to place the ball in the gaps and pick ones and twos. But they are quite often seen hooking and pulling the ball in the air. Since it is difficult to play the ball which is dug in with the bat on top after a low back-lift, such players use the pace of the ball and just tap it to fine or square leg, getting useful runs for themselves and the team.