In many small and medium-sized enterprises (SMEs), assembly workplaces often evolve over time without structured planning. This frequently results in inefficient workflows and suboptimal workplace layouts. A primary reason is the complexity of existing optimization methods, which typically require extensive expert knowledge and are therefore challenging to apply in SMEs. This paper presents the development of a user-friendly methodology for the semi-automated determination of optimal assembly workplace configurations. The methodology integrates both assembly time- and ergonomics-based optimization criteria, allowing both to be considered simultaneously. By incorporating both aspects within the optimization process, the methodology identifies configurations that maximize efficiency while minimizing physical strain on employees. To support data collection in non-digitized workplaces, an augmented reality (AR) application was developed for the Microsoft HoloLens 2. This application assists workers in capturing critical workplace parameters, including component distances, movement sequences, and process flows. The methodology analyses the workplace using a structured combination of primary-secondary analysis, Methods-Time Measurement Universal Analyzer System (MTM-UAS), and a variant of the Rapid Upper Limb Assessment—NEPRA. Afterwards the workplace is optimized by systematically changing the arrangement of all parts containers. The methodology also guides the user through the optimization by providing visual and textual instructions based on the results of the analyses. The proposed methodology provides companies, especially SMEs, with a practical tool for systematic workplace optimization without requiring extensive prior expertise.