I have a couple of questions on using Labrouchere (labby) line. Lets say we have a line that looks like this with the number representing the number of unit: 1 would be one unit, 2 = two units.

1 - 1 - 1 - 1

On the first bet I wager to win 2 units at the odds of 1.25, so I actually lost 2.5 units. So the next labby would look like this

1 - 1 - 1 - 1 - 2.5

My questions are is it best to place the wager to risk or to win the units? How does the varying ML odds affect the labby line?

I want to start using the labby but these points are confusing. Any ideas? Thanks