Fused Deposition Modelling (FDM) is one of the most widely adopted additive manufacturing techniques due to its affordability, flexibility, and capability to produce complex geometries using biodegradable polymers such as polylactic acid (PLA). With the rising demand for reliable, high-performance 3D-printed components in engineering and biomedical sectors, optimising key process parameters to achieve enhanced mechanical strength and surface quality has become increasingly critical. This study examines the effects of selected printing parameters on the compressive strength and surface roughness of FDM-fabricated PLA specimens. A systematic experimental approach was implemented using an L9 Taguchi orthogonal array, enabling efficient planning and analysis of the influence of each parameter. Results indicated that raster orientation had the most significant impact on compressive strength, achieving a maximum of 67 MPa with a ±45° orientation, 210 °C nozzle temperature, 0.1 mm layer thickness, and 60 mm/s printing speed. In terms of surface quality, layer thickness emerged as the dominant factor, with the smoothest finish (Ra = 4.84 µm) achieved at 0.1 mm, 200 °C, 30 mm/s, and ±45° orientation. These findings provide practical insights into parameter optimisation strategies, supporting the production of PLA components with improved structural performance and refined surface characteristics. Such optimisation is vital to expand the applications of FDM-printed PLA in advanced functional, engineering, and biomedical contexts.