Adverbs

1. Feminine form of the noun + -mente

e.g. lento -> lentamente
e.g. inteligente -> inteligentemente
e.g. eficaz -> eficazmente

2. Irregular adverbs

bueno -> bien
malo -> mal

3. It is commonplace to use the masculine adjective in place of an adverb

e.g. Pablo corre rápido.