a safe way i found that works for me is
i would bet on dice high, 1 satoshi, and wait till i see 8+ reds,
and after 8 reds i would bet maybe 1% or so of my bank and start to martingale, after a win i go back to satoshi's fishing for another 8+ reds or so,
ofcourse if you do this long enough, you will lose all.
but theres a chance to win some short term and leave, if your into that!
ps i dont do this anymore because i dont want to test my chances
and dont advise anyone to ever gamble anything they cant afford to lose!