In monosyllabic words, the accent is obvious. In disyllabics and polysyllabic words, the penultimate is stressed if long or followed by two syllables (like crescentes), otherwise the antepultimate gets the stress. E.g. impudicus, laudabo, hortorum, proclivis, etc... are stressed on the penultimate; homines, capsula, epistola, virium, facio, etc are accented on the antepultimate regardless of vowel length.
Others will add their statements.