There are three basic ways to form questions in Spanish: raising intonation at the end of a sentence, inverting the subject and verb, or adding question tags like "¿no?" or "¿verdad?". Questions can also be formed using interrogative words such as "¿qué?", "¿cómo?", "¿dónde?", etc. It is important to use inverted question marks at the beginning and end of written questions.