The type you use for headlines (also called "display" type) can be the same style as the text type or it can be a different style. Whatever you choose to do, the display type and the text type should complement each other.
Use one or two methods to highlight headings. Don’t overdo it:
AVOID HEADLINES LIKE THIS
Lower case letters are easier to read than capital, or upper case letters. They give the reader more visual information about the characteristics of each letter. WORDS MADE UP OF CAPITAL LETTERS ARE SEEN AS BLOCKS AND ARE HARD TO READ, ESPECIALLY IN A PASSAGE OF TEXT. However, short subheadings in capital letters can be used to good effect.
Short lines and narrow columns make the eye shift too quickly and confuse the reader into reading across columns instead of down. Long lines can also be hard to follow. For letters or reports, use left and right margins of 1.2 inches.
Text that has a ragged or uneven right margin (like the paragraph above) is easier to read than text that has a justified or full margin. A justified right margin creates unequal spaces between words and hyphenates many words at the end of lines. Hyphenated words are hard to read, so turn off "hyphenation" when you use a word processor.
(This paragraph was typed with a full margin and hyphenation.)