Those were typically made with lettering guides and French curves (I'd have liked to take a few pictures of mines, but I cannot recall where I put them: hundreds of hours at high school spent using them1). In certain cases, you could have also used dry transfer letters.
In many cases, graphs and drawings were made by professional graphic designers, and that's why many old pictures look so good.
1A typical homework punishment in drawing classes for anyone who made too much noise in class was to fill an A3 sheet with text written with the smallest lettering guide.