<i>"what is a good amount to start with for futures?"</i>
A good amount to begin with while learning to trade is $0. That is, absolutely zero real dollars worked = risked while you learn the game.
No one "earns while they learn". Instead, it is always "learn while you burn" in reality.
Excellent advice given above. You are at the very beginning stages of learning a complex, tough profession. Go to school with virtual money in demo mode. The $22k (or more) you save in the process will be your own!