Russian Capitalization Rules
Capitalize days of the week and names of the months?
No.
Capitalize nationalities and languages?
No. E.g. американец - an American, француз - a Frenchman, русский язык.
Capitalize adjectives derived from proper nouns (containing the suffix -ск)?
No. E.g. московские улицы (the Moscow streets), парижское кафе (a Parisian cafe). Except when forming a proper noun: улица Московская (Moscow St.), Казанский вокзал (Kazan Railway Station).
Capitalize the pronoun я?
No. Only at the beginning of a sentence.
Capitalize compound proper names/titles/holidays (e.g. Black Sea, Atlantic Ocean)?
Only the first member is capitalized: Чёрное море - Black Sea; Атлантический океан - Atlantic Ocean. Except, when the second member is also a proper name (Южная Америка - South America) or referring to high-ranking agencies (Верховный Суд - Supreme Court; Совет Безопасности - Security Council).
Capitalize вы?
Yes when used as a pronoun in correspondence, but no when used as second-person plural. Also, Вас, Вам, etc. are capitalized.
Capitalize simple, one-word, proper names (e.g. Pushkin, Moscow)?
Yes.
Capitalize words at the beginning of a sentence?
Yes.
Capitalize countries?
Yes. E.g. Испáния, Амéриса.
Capitalize possessive adjectives (containing the suffix -ин)?
Yes. E.g. Катина книга - Kate's book, Сашин телефон - Sasha's telephone.