test strips are used by many. I know some people that us e a full sheet and expose it in quarters. Each quarter is at a different grade. I have an analyser pro which works as a light meter. With it you can previsualise the final result. However, it takes a while to calibrate the thing. I highly suggest a stouffer transmission step wedge to calibrate the analyser pro. I use a reflection densitometer to set the final results on the paper up.