This paper addresses several critical aspects of using optically pumped magnetometers (OPMs), focusing on both metrological issues and the enhancement of signal quality. We present a quantitative methodology for OPM measurements standardization and quality evaluation, which is crucial in biomedical applications like magnetoencephalography (MEG). Additionally, we introduce a novel, cost-effective portable active magnetic shielding system – digital adaptive suppression system (DASS) – that represents a significant advancement over traditional analog active shielding. Through comprehensive experimental research, we evaluate first- and third-generation commercial OPMs from QuSpin Inc. in two distinct magnetic environments. Our results demonstrate that the DASS ensures optimal and reliable OPM performance, even in noisy urban settings, surpassing the effectiveness of conventional analog shielding. These findings highlight the need for advanced magnetic shielding solutions to enhance the accuracy and reproducibility of OPM measurements.