Some BJ players have built up their bankroll quickly using what I call the "Hail Mary" bankroll technique.
In football, as you probably already know, a Hail Mary pass is a go-for-broke pass in the closing moments of the game. A quarterback throwing a Hail Mary pass is going for the victory with one dramatic play.
The Hail Mary bankroll principle is that you bet big for the size of your bankroll. If you happen to catch a big positive fluctuation, (i.e., complete the pass) then you end up with a big bankroll, at which time you start betting very prudently for the long haul. If, however, you tap out your Hail Mary bankroll, then you save up another bankroll and do the Hail Mary procedure over again.
This can be a good approach for those who can comfortably regenerate their bankroll in between gambling trips (from a job or other income).
What's really good is that, unlike in a football game, the clock never runs out for the BJ player using the Hail Mary technique, assuming new Hail Mary bankrolls can be readily generated.
Size your bets for the Hail Mary bankroll so that the risk of ruin is reasonably small for duration of the trip only; do not size your bets for survival over the long haul. Eventually, and hopefully sooner rather than later, you'll catch a real positive flux rocket ride, and be in business at a higher level.
A loose rule of thumb is to have about 40-50 of your maximum bets for a Hail Mary gambling trip. A much more precise strategy can be determined by using a good simulator and plugging in your particular variables, such as anticiapted hours of play, rules, bet spread, number of decks, etc. Also, if you really want to "swing for the fences" (sports metaphor party here) you can jack up your bets more and more as your trip winds down, assuming the same bankroll. With one hour to go for your trip, you could obviously bet a whole lot bigger on the same bankroll than if you had 30 hours to go for your trip.