The Liferay schema encoding should always match the encoding used in the database. One of the easiest ways to do this is to simply use UTF-8 across the board so that no issues arise.
Resolution
If you decide use international characters or characters with accents on them, any other encoding may have issues when these characters are being read from the database. It is therefore advisable to use UTF-8 for internationalization. If ISO encodings are used, ensure that only English Western characters are used (meaning that no accents are allowed.)
Be very specific when first setting up the database to ensure that the encoding stays at UTF-8. If it is not, data conversion may be necessary if internationalization is required in the future.