Hi ludako,
Check out: https://www.roulette-bet.com/2015/02/mathematical-proof-that-progressions.html
IMO you need to show with paper trading a long-term* positive expectation with your selection method.
Once you can show a paper long-term profit (ie an "edge") then some variant of Kelly betting is my preference (ie bet according to your "edge").
Basically, if you don't have an edge, don't bet!
* What is long-term?
Varies depending on what you bet on, for me and horse racing it is 750 races.
HTH, benko