Know the probability of account ruin before it happens.
Risk of ruin is the probability of losing a defined percentage of your account given your trading parameters. Even with a positive edge, reckless position sizing can make ruin near-certain.
The two fastest ways to reduce risk of ruin: (1) lower your risk per trade, and (2) improve your win rate or payoff ratio. Targeting below 5% risk of ruin is a reasonable threshold for funded account trading.