The method I use is to start with 0.001 & see how much I can profit or lose from that.
There have been a few times I've got as high as 0.016 from 0.001.
When I win that much I make bad decisions and always lose it all.
Managing greed & emotions & maintaining self control is what I have the most trouble with.
Even if I'm losing I feel like it is a good therapy to learn not to worship money and resist it influencing me.
You're exactly right. Once we win, greed and emotion takes over ending up losing everything then start all over. Its really hard to control these because the feelings of winning makes you want to win more and bet more than you originally intended.