Do only 50% bet 20$ every time if it fails do 60$ it fails do 150$ if it fails do 350$ if it fails do 900$ if it fails do 2300$
There is no way you will fail 7 times and if you do just increase the bet and you will get it back eventually even if you wait 12 times.
what you think on my method?
I followed this strategy in many times specially in CASINO but i lost big amount of money, because you can't win every bet. Even i waited 15 times then i have no dollar to bet for next one, as a result i lost everything. So, i would like to recommend don’t start bet with big amount like 20$, you can start 1$ if you have big amount then start 5$-10$. There is a high possibility of losing everything if you get too greedy.