One thing I used to do is Handicap match " 讓分"
Start with 10:0 (he got 10 points)
He would work his way up, 9:0 (u serve once in first turn), 8:0 and so on
This way you have the pressure of not losing points and he can have a good index of how good he is.
Another way of Handicap is limited your skill "讓技"
Not to use certain skill or even use left hand, this is useful, for example, if his peer don't know looping against backspin, then don't use it. This would give him more or less the real match feel law!