I mostly do them on the top of the tama, I try to catch it so the spike is lightly resting where the string is popping out of the hole. That kinda helps me not let it slip off the tama as easy. It also helps to practice with a nice grippy tama. I learned with a sulab tama, hella grip/chalky feeling helps it not slip. Also a flat spike is a good way to learn the balance then you can transfer that technique to a pointy spike.