I want to state a basic example of Positive Progression Wagering.  IMO, I believe the 1-3-2-6 is the most lucrative and easiest to capture, while protecting the gambler of ruin, due to losing his realization of around the corner losses upcoming.

Remember, there are many variations, with denominations galore in Positive Progression Wagering. 

1-3-2-6. (Exampled using $100.00 unit):

Wagers:

First bet:  $100.00
Second bet:  $300.00
Third bet:  $200.00
Fourth bet:  $600.00

Reasonings:

First bet is a portion of your risk capital buy-in.  If you lose, you lost 1 unit of your risk capital.  If you win, parlay and move on to the second bet.

Second bet is parlaying your win and 1 additional unit from your risk capital buy-in for a $300.00 wager.  If you lost, you return to 1 unit wagering and you are down 2 units.

Third bet means you won your second wager.  Now you are in great position!  You return $200.00 to your buy-in stack, you set-aside $200.00 and you wager the remaining $200.00 from your $600.00 end of 2nd bet, on your third wager.  If you lose this wager, you are still $200.00 ahead for additional  wagering attempts at $100.00 each.  If you win this third bet you move to the fourth wager.

Fourth bet will progress to $600.00.  You will parlay the third bet win and add the $200.00 you had set-aside with a win from the second bet.  You have zero risk capital out there and a total wager of $600.00 looking for a $1,200.00 win.  If you lose, sure it sucks, but you didn't lose a penny of risk capital. 

If you win the fourth bet, you must go back to one unit wagering and right there is exactly where almost all players go down the wrong path and will greatly increase their wagering amounts with doom waiting. I would personally go back to the same amount or possibly 1.5 times, or a max of double.  Example.  If I was wagering the above $100.00 unit, I would start again with $100.00 or possibly $200.00.