Use plain language
Say what the player should do next before explaining every reason behind the rule.

Teach Mahjong
Enough structure to play, enough room to enjoy it
Suggested lesson flow
Let players touch and sort real tiles before you introduce the card.
Show one completed hand so learners know what they're building toward.
Use a simple line to explain colors, suits, groups, and spacing.
Do a guided Charleston and an open hand practice game.
Teaching philosophy
New players don't need every exception in lesson one. Give the main rule, let them experience it, then layer in details as they become relevant.
Say what the player should do next before explaining every reason behind the rule.
In a teaching game, open hands let the whole table learn from each decision.
Visual supports let learners solve small questions while you help someone else.
My teaching resource
A printable step by step handbook for instructors, friends teaching friends, and anyone who wants a clear structure for introducing new players.