By martingale i don't mean to double up on the same position and wait till the market turn around,but when i use a system,wich has a specific pattern of loosing trades and winning trades,such as 3,4 or 5 loosing trades and then a winning trade,then i use the martingale,i double the size eachtime i have a loosing trade till i have the winning one.
I have to mention there are two ways doing this,first the geometric martingale which is to double the size after each loss.
second the arithmetic martingale which is much less dangerous,i just add one unit after each loss.
so the geometric will look like this 1,2,4,8,16,32....
while the arithmetic will look like 1,2,3,4,5,6......
(consider those number being number of lots you are trading)
the problem is if you have an unexpected high consecutive loosing trades ( 10 or 20) but as long as your consecutive loss are under control,i think the martingale is a very good idea