What was the amount with which you started trading
I mean your very basic investment and was that your extra money or required money?
The best amount and the one that I were starting with is $500 because it is not so painful if you will lose it and it is enough to start something good here without childish play.
Actually buddy, there is minimum amount in trading site which will compensate the amount of the tradable coins that you have. Also, it depends the kind of trading site in which their is minimum and maximum as well as the value of gas to use in trading process.