This manual provides a structured guideline for assessing carbon sequestration capacity in wetland ecosystems within the Restore4Life project, with the aim of supporting a widely applicable and citizen science (CS)-suitable monitoring scheme. It compiles and evaluates a selection of field-based and geospatial methods, presented through standardised factsheets that describe their applicability, requirements, and limitations. The manual applies a transparent evaluation framework based on measurement characteristics and process-scale to support method comparison and selection. It highlights that individual methods capture only specific components of the carbon cycle and therefore represent partial estimates of carbon sequestration, requiring careful interpretation and, where appropriate, combination of approaches. Practical guidance is provided to support method selection.