Most capitalisation mistakes come from over-capitalising, not under-capitalising — treating a word as important enough to deserve a capital when the rule doesn't actually require one. The core rule is simple: capitals mark specific, named things, not general categories or emphasis.
Titles, seasons and directions
Job titles are capitalised only when they're used as part of someone's name, not when they describe a role. "I spoke to Marketing Director Jane Ellis" takes a capital because the title sits directly before the name; "Jane Ellis, the marketing director, called" does not, because here it's just describing what she does.
Seasons — spring, summer, autumn, winter — are never capitalised unless they open a sentence or start a proper name like "Summer Olympics." Compass directions follow the same logic: "drive north" stays lowercase, but "the American South" is capitalised because it names a specific region, not just a direction of travel.
What actually counts as a proper noun
The test for a proper noun is whether it names one specific, unique thing rather than a type of thing. "University" is a common noun ("she works at a university"), but "the University of Leeds" is a proper noun. The same word can be both depending on use: "my mother" stays lowercase, but "I asked Mother" capitalises it because here it's being used as her name, standing in for it directly.
Departments, subjects and programmes cause the most confusion. "She's studying history" stays lowercase because history is a general subject; "She's enrolled in the History and Politics programme at the college" capitalises the specific, named programme.
When in doubt, default to lowercase
If you're unsure whether something is specific enough to earn a capital, lowercase is the safer guess — over-capitalising reads as amateurish or overly formal far more often than under-capitalising does. Reserve capitals for the things that would be capitalised on an official document: a specific title before a name, a specific place, a specific institution.
A quick check before you publish: search your document for capitalised words and ask, for each one, "is this naming one particular thing, or just describing a category?" If it's a category, lowercase it.
