I agree that you don't want to over leverage.
I never trade more than 1 ES per $3k, or 1 ER2 per $5k. otherwise you are going to have really high percentage losses from time to time, and if ya get in a bad streak, yer screwed, The only exception to this is if you are scalping a few tics per trade, and have a stop of a few tics per trade. This is very difficult however.
Jay