Tip no. 3: Of widows and orphans
You see them more and more. Individual lines that stand alone at the beginning or end of a column or page. In a better time, when it was still part of good craftsmanship to strive for an undisturbed reading flow, both were regarded as typographical cardinal errors that had to be avoided at all costs. These mistakes even had memorable names, as was customary in typesetting: The single line that had been lost in the previous column was called an “widow”; the one that had been lost and had slipped into the next column was called a “orphan” (whereby the “orphan” is regarded as the worse of both evils because it disturbs the reading flow even more than the “widow”).
It is not particularly difficult to avoid these errors in digital times. Almost every word processor (and even more every professional typesetting program) has a corresponding paragraph rule (see Wikipedia). Usually you can specify the number of lines to be kept together at the beginning or end of a paragraph. So these errors don’t stand a chance anymore. If the space at the beginning or end of the column is no longer sufficient for the specified number of lines, the paragraph is divided so that these lines are in the next column. Sometimes there will be a gap at the end of the previous column, but it is much less disturbing than an orphan.
And if you really want to do it well, then you just insert an additional paragraph in another place where it makes sense and thus also avoid the gap.