from reading your post, i realize you are using too much 'racing' technique in this.
1. if you tend to lose the cars tail, then it likely has a tenancy to be too lose, or the front is getting too much grip. (increase negative camber/reduce sway bar in back)
2. i started with doing little power-over steer drifts whenever i could in the corner, and working my angle up. as the angle increased, so did the length of the drifts. along came control.
3. too much speed will just be hard to start, and end the drift, a loose set with not much speed (i like my sets to have very low gearing for ease of throttle control). this will let you stay slow, but with a jerk of the throttle, your rear will be loose.
go to the autocross, and try to drift a circle. this will teach you throttle control, and input in general.
this will be difficult.