How about to say actual words that contain "r"? The pronunciation of "r" is a bit different depending on the vowel following it or the position in the word("ra, ru, re, ro" vs "ri" or "at the begining of the word, after n" vs "in the middle or at the end of the word").
I haven't listened, but the way I learned to do it was this:
Place the tongue in the d-position in your mouth, and from there make an r sound. It should have a flick to it. The English r can be extended (rrrrrrrr) but the Japanese r is more percussive.