Slotting the club behind the body is a tough a thing to do for mist golfers. Visually the club feels too far behind them. That's why there is a method to the learning of the drills in an order that works. Watch the slot become better on this student in this video.
Over the top swing planes are tough to fix just by thinking your way out of that move. Here is a driving range tip to help shift that path to better.
The way the shoulders work on the backswing and downswing can be different. Learn from this video the correct movement of the shoulders. I call this the difference between a Ferris wheel and a merry go round. 
Can a golf swing really work up and down on one plane? Theorists believe so. Let me explain why that generally can't happen.
Learning to improve the swing path on the downswing and entry sometimes needs to be a little abstract. I changed this student below downswing path from the left to right from this one crazy awareness and feel.
Flat versus upright. I m not talking about the swing itself but the equipment. Remember the shape of the swing is not based on address or the top- its how things begin to work on the downswing and then impact