capitalization: sentence case / title case

Sentence case caps the first word and proper names: How to write a will. Title case caps nouns, pronouns, verbs, adjectives, and adverbs: How to Write a Will. It leaves articles, prepositions, and coordinating conjunctions lowercase unless they stand first or last. Either system is standard. Pick one for a document and keep it. Do not mix them in the same list of headings.