Only risk what you can afford to lose
A price is a probability, not a promise. Any single position can go to zero.
Set limits before you start
Decide a maximum amount per week and per position, and stick to it. Position-sizing methods such as Kelly are guides, not guarantees; many traders use a fraction of the suggested size.
Warning signs
Chasing losses, trading money meant for bills, or hiding trading from people close to you are signs to stop and seek help from a local support service.
Age and local rules
You must be an adult and follow the laws of the country you live in.