Software measurement currently plays a crucial role in software engineering. It helps analysing both quality and productivity of the developed or maintained software. COSMIC–FFP, the COmmon Software Measurement International Consortium Full Functional Point (CFFP) is a measurement methodology designed to estimate the functional size of software. While bundled with comprehensive guidelines, the practical application of COSMIC is not trivial and experience plays an important role for its successful application. The objective of this paper is to provide practitioners with hints and additional recommendations learnt from applying CFFP to significant industrial cases. More specifically this paper will focus on the latest COSMIC (COSMIC V3.0) which comes with new concepts and for which there is still not much experience returns from its application. This paper relies on two significant case studies covering different domains : a wide-scale web application for a European commission administration and a modular application to be used jointly by five Belgian federal and regional parliaments. Different measurement contexts are also considered especially initial estimation vs application enhancement.