Hitting a flop shot off a tight lie requires that you attack the ball with a steeper swing and open clubface so that the club gets under the ball and pops it up softly
Using a piece of string with tees attached to both ends is the best set up and alignment tool you can have, put it in the ground to represent your target line then use it to square your clubface, align your body to the target line and maintain a constant ball position
This drill is great for people stuck in an office or in bad weather, hook the right hand under the left and practice your backswing and downswing with a perfect right and left wrist position