Finally figured out the difference between ث and ذ and ظ
Like most english speakers, I immediately identified these sounds with our "th" sound. This is a mistake. Just as "th" has many different sounds in english ("those" "teeth" "thought"), so does the arabic.
ث - "teeTH"
ذ - "THose"
ظ - "THought"
I've recorded myself saying them, in order. Please feel free to correct my pronunciation.