Learn Italian: Marco studia ogni sera. È una buona abitudine. - Marco studies every evening. It is a good habit.

Both mean the same thing, but their grammar is different. Ogni means "every" or "each" and must always be followed by a singular noun without an article (ogni sera). If you want to use tutte (all), you have to use a plural noun and include the article: tutte le sere (literally "all the evenings").

Could I say ogni sere?

No, because ogni is invariable. This means it never changes its ending to match masculine or feminine, and it only ever pairs with singular nouns.

The word abitudine ends in "-e". How can I tell if it's masculine or feminine?

Nouns ending in "-e" can be tricky, but you can look at the words around it! The feminine article una and the feminine adjective buona tell us that abitudine is feminine. As a handy tip, Italian nouns ending in -udine are almost always feminine.

Why does buona come before the noun abitudine? I thought adjectives went after the noun.

Most descriptive adjectives do go after the noun in Italian. However, a small group of very common adjectives—like buono (good), bello (beautiful), and brutto (bad/ugly)—usually come before the noun.