Only a few adjectives go before the noun, the rest are placed right after it.  Bello-beautiful, buono-good, grande-large, and brutto-ugly are the most common preceding adjectives, even though they don't have to go before the noun.  Bello and buono have alternate forms when they precede a noun.

If they go after the noun, then they can be formed in the usual way.  The above forms are only for when they go before the noun.  Be aware that grande can have alternate forms before nouns too.  Grande can become gran before masculine or feminine nouns beginning with a consonant.  Or it could contract to grand' before masculine or feminine nouns beginning with a vowel.  But you do not have to use the alternate forms, whether or not you place the adjective before or after the noun.