One of the most basic drills I use for developing the proper start of the takeaway and to help get the clubface square at impact, is the Toe Up-Toe Up Drill.
Start out by making a short swing, right at your hip or belt buckle height on the backswing, then make a short follow-through swing hitting the ball and stopping halfway with the club/shaft pointing to your target. When the club is hip high on both the backswing and follow-through, the toe of the club should be pointing to the sky.
This drill will help you achieve what the hands and arms are doing on the backswing and follow-through, as well as help you ingrain the correct feeling of how to get the clubface square at impact. After creating the toe up positions on the hip high swing, increase the size of the swing until you eventually have a full swing.
Always remember to “Practice with a Purpose” – Chip Inks, PGA