Let me give two cautions. 1) The one is, that you keep them to the practice of what you would have grow into a habit with them, by kind words, and gentle admonitions, rather as minding them of what they forget, than by harsh rebukes and chiding, as if they were wilfully guilty. 2) Another thing you are to take care of, is, not to endeavour to settle too many habits at once, lest by variety you confound them, and so perfect none. When constant custom has made any one thing easy and natural to 'em, and they practice it without reflection, you may then go on to another.

Sec. 66 - Some Thoughts Concerning Education (1693)