Handbrake Settings?

So I have slowly but surely started ripping my BluRay library onto my PC using MakeMKV. As expected, my harddrive space is diminishing quickly. I have read compressing the mkv file will decrease size drastically. I do not have much handbrake experience and do not know what settings to use that will give me the best results in both areas: maintain great HD quality and smaller file sizes. Note: I'm only keeping DolbyDigital and DTS Audio. (aka no HD AUDIO)