Just practice practice practice. When I started drifting I was terrible at it. But being a grip racer by heart this was not surprising. However I stuck with it, and now I routinely manage top 500 placements on the seasonal drift events in many different cars.
If I had to recommend drifters I'd go for the S13 Silvia K's and TVR Tamora to start with. But my fav has to be the Lexus LFA, though that is a rather tricky car to drift without experience. But more gratifying when you get it right. And the noise, my god the awesome noise! Same goes for the Blitz ER34.
As for my speed it depends on the track. Slower tracks about 50-80 km/h.
Medium tracks about 80-120 km/h. Fast tracks 120 + + + km/h.
I have drifted my LFA seccuessfully at close to 200 km/h.
Road Course Indy I avg. about 65-85kph IN the drifts but initiate at speeds of up to 130kph but it varies. I would say 70kph is probably my avg..which is almost 45mph.