I know that the answer to my attention-grabbing question is : "You can't win at roulette, it's a negative Expected Value game".
Yes, you're right, long term speaking.
Let's imagine a medium-short term situation (just an after-dinner at the casinò) where there will be <100 bets.
What's the best strategy to use to win some money?
I imagine a hypothetical formula that considers our "money target" and percentage of success as inversely proportional (the more we want to win the less likely we are going to succeed).
What do you think? Are those "red-black double if lose" systems useful?