Best thermometer for BBT

Hi everyone! So I started Clomid today and I have been given a chart to put in my bbt every day. My doctor gave me of one to refer to and it looks like they didn't take their temp on menstruation days, so do I just only record my temp on days I'm not having my period? Also, it says use a metabolic thermometer. Does that really matter or are digital ones just as fine? Since its the weekend I cant really call my doctor to ask so I figured id ask all you wonderful ladies!