Unit sizing
Your unit should be small enough that normal variance does not destroy the bankroll. Conservative plans use more bankroll units; aggressive plans accept deeper drawdowns.
Risk of ruin
Risk of ruin estimates the chance the bankroll is depleted before the long-run edge can materialize. It improves with bigger bankroll, smaller unit, better edge, and lower variance.
Session controls
Stop losses and win targets do not change the math of a game, but they protect discipline and reduce the chance that one session forces bad decisions.