The amount you trade depends on your willingness to lose money. However, if that's covered, then you should look at the volume of the asset you intend to trade and try to stay lean.
Better to trade with as low as 0.01BTC rather than satoshis. Let the amount be as significant that a plausible profit can be earned. Trade only as much as you can afford to lose at that moment. That will give you a better idea of the risk but for the profit - the sky is the limit my friend.