Seat out Forwards and Backwards
Seat out front and Back are what I think the essential things needed to learn Seat Push and Seat Drag. To start off with the grip and the positioning to the body has to be as close as it can be. Here's where I hold the seat when I do this. If you can do seat out front hopping then this is a nice start. If not just get the unicycle by the wall and level the pedals at horizontal and simply stand up and take the seat out either in front or behind. Just stay by the wall idling for 5 minutes getting used to where the balance shifts. When you get the hang of that simply just ride along the wall :) When u get the hang of that just move away from the wall.
Seat out Backwards is slightly harder because you cant put as much pressure on the seat as forwards. Learn both at the same time.
Tip, Use the seat - its there for that reason. Try to be as light as possible on the pedals, If your having trouble try putting most of the weight on the seat with the arms.