What part of my back foot should be placed on the tail? The ball or the meaty part?
Try putting the arch of your foot over the tail or truck. If your in a top mount, your feet need to be sideways. Slowly add pressure to your back foot or until you start manualling.
I have two approaches deapending on your deck shape I personally find having the side of my foot facing out and parallel to the truck for maximum balance and remember keep your arms up for balance
The ball of your foot