Directional Signal: These are unidirectional. A "VGA to HDMI" converter only works to connect a VGA-output source (like an old laptop) to an HDMI-input display (like a new TV). It will not work in reverse.
Audio Support: Since VGA is video-only, ensure your converter has a built-in audio cable to capture sound.
Power Supply: Most converters require a USB connection to power the internal chip that translates the signal from analog to digital.
Resolution: Most standard converters support up to 1080p Full HD at 60Hz.