Software Process Improvement (SPI) methodology is defined as definitions of sequence of tasks, tools and techniques to be performed to plan and implement improvement activities. Well-known SPI frameworks like CMMI and ISO/IEC 15504 define SPI methodologies in an abstract manner. We developed an SPI methodology, BG-SPI. providing a ready-to-use SPI scheme with guidance on an iterative SPI lifecycle, composed of task definitions with details on resources, tools, roles, participation of groups, process assets, and other process specific supporting items. Utilizing BG-SPI with support of SPI experts. organizations can easily plan and manage SPI lifecycle. BG-SPI methodology is applied over 10 organizations with different size, sectors and SPI motivations. This paper explains BG-SPI and provide insight on how a detailed SPI methodology helps the SPI projects in various aspects.