Keep your hands under your shoulders throughout the entire golf swing in order to develop a consistent club path during the swing
In the one plane swing takeaway the left arm comes across the chest and the right arm retracts behind you, causing the club to come back more to the inside than on a two plane swing.
If you commonly come over the top and slice the ball the one plane swing is a great solution because you are bent over more and naturally attack the ball from the inside.