A number of approaches have been proposed for the problem of digital preservation, and the number of tools offering solutions is steadily increasing. However, the decision making procedures are still largely ad-hoc actions. Especially, the process of selecting the most suitable preservation action tool as one of the key issues in preservation planning has not been sufficiently standardised in practice. The Open Archival Information Systems (OAIS) model and corresponding criteria catalogues for trustworthy repositories specify requirements that such a process should fulfill, but do not provide concrete guidance. This article describes a systematic approach for evaluating potential alternatives for preservation actions and building thoroughly defined, accountable preservation plans for keeping digital content alive over time. In this approach, preservation planners empirically evaluate potential action components in a controlled environment and select the most suitable one with respect to the particular requirements of a given setting. The method follows a variation of utility analysis to support multi-criteria decision making procedures in digital preservation planning. The selection procedure leads to well-documented, well-argued and transparent decisions that can be reproduced and revisited at a later point of time. We describe the context and foundation of the approach, discuss the definition of a preservation plan and describe the components that we consider necessary to constitute a solid and complete preservation plan. We then describe a repeatable workflow for accountable decision making in preservation planning. We analyse and discuss experiences in applying this workflow in case studies. We further set the approach in relation to the OAIS model and show how it supports criteria for trustworthy repositories. Finally, we present a planning tool supporting the workflow and point out directions for future research.