Use a character set appropriate for your localization language. For example, single-byte language character sets typically require UTF-8, while a multi-byte language may require a UTF-16 character set.
The character set you choose may impact field sizes. For example, a Varchar(40) field can only store 40/3 Japanese characters using the UTF-8 character set. This has implications on the table field sizes at the time of creation. Table creation scripts must be modified to ensure that the field lengths are correct.