This chapter discusses the methodological approach for natural assurance schemes (NAS). We developed and applied methodologies and strategies to increase the readiness in technology (TRL), institutions (IRL) and investment/financing (IVRL) and illustrated them in contrasting case studies. To assess how readiness is crafted to effectively green water risk reduction and water security plans, we propose an integrated analytical framework that builds on participatory adaptive planning approaches. Through an ex-post expert assessment of NAS implementation in 9 case studies, we demonstrate how methodologies and strategies to increase TRL, IRL and IVRL can contribute to operationalization of NAS under a wide range of contexts and boundary conditions. Case studies have (1) varying biophysical conditions, spatial scale and vulnerability to water related natural hazards that require diverse NAS approaches, but also (2) varying readiness levels for implementation of nature based solutions in NAS. Institutional readiness is generated throughout the entire planning process, through a combination of joint assessment of risk perceptions and the institutional set-up as well as facilitation of awareness and agreement on responsibilities. Investment readiness is generated through the generation of the NAS business canvas and can be translated into investment plans built around the 5 business cases proposed in the Financing Framework for water security. We illustrate that for nature-based solutions (NBS) to be integrated in water security and climate adaptation strategies effectively, the NAS approach needs to craft readiness at all levels, tailoring an integrated set of methods and tools available through a collaborative process with stakeholders.