Toss is slightly farther back.
Impact zone is slightly LOWER than for a flat serve.
Use slightly more backhand grip, but still try to pronate up and thru the ball, or it spins TOO much.
Aim 3' above the net cord.
Slow down your second serve by at least 30% to allow your topspin to arc the ball down into the court with the help of gravity and air drag.
And swing slightly FASTER than you did on the first serve.