MARTINGALE STRATEGY:

This strategy is very simple and looks very attractive and profitable. BUT it's not 100%, not even 90%, it's something under 50%!!, So that means that it's not guaranteed profit. Let's say that you have unlimited amount of money and unlimited maximum bet. Then you can say it's 99,99999 etc.%. Because nothing can be 100%.
- And now what Martingale strategy basically means:
This strategy tells you that you can always earn amount that you bet at start. When you are using real money it's best to start with 1$ or if you have big amount of money and you are feeling lucky then you can use 2$ or even 4$ but i don't recommend that. You can regret it.
So the system is following:
Let's start with that 1$ (i am really unlucky person):
You can now choose between red or black, even or odd, 1 to 18 (Manque) or 19 to 36 (Passe)
So let's choose red or black, we will bet on one of these color. I like black so i will choose that one.
And now some theory.
You bet 1$ on black and wait.
(If you win you will get 2$. so profit 1$)
If you lose DOUBLE your amount on same color.
So you have now 3$ "in game"
(If you win you will get 4$, so again profit 1$)
Again there is a chance you will lose so all you have to do is what? DOUBLE your amount on same color!
Then you have 7$ "in game"
(If you win you will get 8$, so surprisingly profit 1$)
And you can go like this forever.... If you have that much money of course.
In shortcut it look like this:
1. Bet 1$     - Possible win 2$
2. Bet 2$     - Possible win 4$
3. Bet 4$     - Possible win 8$
4. Bet 8$     - Possible win 16$
5. Bet 16$   - Possible win 32$
6. Bet 32$   - Possible win 64$
7. Bet 64$   - Possible win 128$
8. Bet 128$ - Possible win 256$
9. Bet 256$ - Possible win 512$
So as i said you have to start with huge amount of money if you want this strategy to really work. If you think that it's impossible to get same color 9 times in row then you are mistaken. I already saw same color 13 times in a row. And that's 4,096$. Ridiculous amount of money just for profit of 1$.
And one more problem is LIMIT. Almost every Casino has maximum bet limit around 50-500$. That means if you bet at black and you lose 9 times in row. You are screwed because you can't bet 512$ due to maximum bet limit.