Don't be afraid to 'play around with it'. You may need different amounts for different teas. Also you can vary your brewing times. I had an assam that I had to keep playing with to get it to perfect. For me I found that it was pretty unforgiving in terms of steeping too long, so I used more tea and a shorter brewing time.
Tea in many ways is more art than science... it's just being able to repeat that art over and over again reliably that's the trick