If you create a compound index for the columns, make sure that the query attributes are in the same order as the index attributes, so that the DBMS can use the index while processing the query. If the query and index attribute orders are not aligned, then the DBMS might be unable to use the index during query processing.
CREATE INDEX TelephoneBook ON Accounts(last_name, first_name)
SELECT * FROM Accounts ORDER BY first_name, last_name