After a little practice these things will become natural and you will thus acquire a habit of writing correctly and well.
General Washington was a remarkable instance of what I have now recommended to you.

His letters are a perfect model for epistolary writers.

They are written with great uniformity in respect to the handwriting and disposition of the several parts of the letter.

I will show you some of his letters when I have the pleasure of seeing you next vacation, and when I shall expect to find you much improved.
Your natural disposition, my dear son, renders it proper for me earnestly to recommend to you to _attend to one thing at a time_.

It is impossible that you can do two things well at the same time, and I would, therefore, never have you attempt it.