Ok
this is an area i have no idea on?!?!?
I am doing BFL , gaining noticeable muscle ( )
But the weight is staying the same (fine by me)
but to realise my progress in a numeric figure, i need to measure body fat??
what is the best way???
i have heard of the caliper way to measure (doesn't sound too accurate to me)
also scales that measure it?
do they work? how well? they just don't go on height and weight (much like BMI) do they actually detect the level of fat?

I use a scale that measures body fat and like it. I don't necessarily consider it highly accurate (although in my case it seems to be about right) but it does give me a benchmark of my progress. As long as the number is going down, I'm happy. Personally, I've found all of the readily available means for measuring bodyfat to have their pros and cons with none of them being particularly more accurate than the next. There are just too many variables that can affect your overall results. I'd suggest picking the one that is most convenient for you and sticking with it. But, as I said before, the actual percentage isn't what is important to me right now but that it is moving in the right direction. Besides, if you ask me, the best indicator of your overall body fat percentage is a good long look in the mirror!