This is what I've been doing:
Each serie has the maximum number of repetitions I can do. So, the first serie is 10 reps then the next serie is 7 and so on, until I cannot lift my weight.
Each repetition is done at a moderate speed and without any delay between reps.
After each serie I rest for at least 15 mins (not sure if it's too much) so that the effect of the lactic acid should be gone by them (not sure if that is true either).
I don't use weights, and I'm a skinny guy (about 155 lb. or 70 Kg)
Lastly I rest for two days before repeating the same routine.