This chapter presents a practical framework for guiding the digitalisation of maintenance processes. It introduces a structured, step-by-step methodology covering the main phases of digital transformation. The guide includes assessing current practices, defining goals, selecting technologies, and building data infrastructure. Its purpose is to support maintenance professionals in transitioning from manual to digital systems. The approach emphasises the use of structured data models and scalable digital tools. A real-world case study is included to demonstrate the methodology in action. The case focuses on the digitalisation of the Certificate of Aptitude for Service (CAS) process in the railway sector.