Aluminum straight plate fin heat sink geometry was modified with vertical sinusoidal wave profile on the fins for different amplitudes. The heat sink fins were further modified by means of circular perforations with increasing diameters. Fully experimental examination was adopted for conducting the work. The heat sinks were assessed on a heat source to see the effect of the modifications on the heat sink fins in terms of heat sink base plate temperature. Heat source was controlled so that the natural convection heat transfer remained in the laminar regime. The experimental methodology elaborately described to share practical experiences on implicit nature and critical points of the commonly used approaches. Up to 40 W heat dissipation is realized with the heat sinks while 2.5 × 106 Rayleigh number value bases a limit for the natural convection potential. The perforations on the fins reduce the performance difference between different wave form amplitudes towards the favorable direction. The 3 mm and 6 mm perforations on the sinusoidally wavy fin profile with 1 mm amplitude value result the least base plate surface temperatures. Therefore, when the cost is justified by the performance improvement, perforations on plate fin heat sinks are recommended in terms of passive cooling applications. In terms of thermal application, present results indicate thermal performance increase of plate fin heat sinks by perforations on the fin surfaces. The experiences throughout the experimental process in the present work reveal unintuitive, implicit, and covert phenomena about the insulation box design and heating power measurement, which are elucidated in the present content. Insulation box can function as an additional heat dissipation surface at the proximity of the heat sink based on the box design. The voltage measurement approach, which is shallowly mentioned in the literature most of the time, can have an effect on the absolute values of the heat dissipation value.