I can also support the consensus here that segments are generally the easiest/cheapest/fastest way to earn status in FB - unless one does several l/h J trips each year, with short xxx-AMS or xxx-CDG connections (which give you 3,750 level miles on a r/t itinerary).
For the past 4 years I've reached Platinum purely on segments (little or no opportunity for l/h J trips); however, this year, things look rather different: I've had one l/h J (EUR-AMS-KUL-CDG-EUR) plus a r/t J on GA (KUL-CGK-DPS), which already has me on 24,000+ level miles. I have a European 4-segment r/t coming up, then another l/h J (AMS-CDG-JNB-NBO-AMS).
As it happens, I'll reach 25,000 level miles and 15 segments on exactly the same flight! But, thereafter, things start to drift apart, and I project reaching 40,000 miles on my 19th segment. With a couple of extra EUR-AMS/CDG-(L/H) trips later in the year, I expect to hit 70,000 miles on or around my 31st segment (and, hopefully, a few other l/h trips towards the end of the year will give a good roll-over boost to get 2016 going).
In terms of cost, if you shop around, you can find some decent prices for l/h J on SkyTeam partners: e.g. FCO-TPE-AKL on CI in "C" for ~£2,000, giving 29,000 level miles (or I've seen LHR-PVG-SYD on MU for about the same price); and don't forget AZ: their l/h biz fares generally earn 150% (^) and I've seen some very decent prices on routes like LIN-FCO-EZE.
-- Henry